U.S. patent application number 12/526266 was filed with the patent office on 2010-03-25 for bone implant.
This patent application is currently assigned to N.M.B. Medical Applications Ltd. Invention is credited to Mordechay Beyar, Elad Einav, Oren Globerman.
Application Number | 20100076503 12/526266 |
Document ID | / |
Family ID | 39682187 |
Filed Date | 2010-03-25 |
United States Patent
Application |
20100076503 |
Kind Code |
A1 |
Beyar; Mordechay ; et
al. |
March 25, 2010 |
BONE IMPLANT
Abstract
A method of long bone strengthening and a composite implant for
such strengthening. Also disclosed is a kit for building a
composite implant in-situ in long bones. In an exemplary embodiment
of the invention, the implant comprises a plurality of rigid
tensile rods, in matrix of cement and surrounded by a partially
porous bag.
Inventors: |
Beyar; Mordechay; (Herzlia
Pituach, IL) ; Globerman; Oren; (Herzlia Pituach,
IL) ; Einav; Elad; (Zikhron-Yaakov, IL) |
Correspondence
Address: |
MARTIN D. MOYNIHAN d/b/a PRTSI, INC.
P.O. BOX 16446
ARLINGTON
VA
22215
US
|
Assignee: |
N.M.B. Medical Applications
Ltd
Herzlia
IL
|
Family ID: |
39682187 |
Appl. No.: |
12/526266 |
Filed: |
February 7, 2008 |
PCT Filed: |
February 7, 2008 |
PCT NO: |
PCT/IL08/00171 |
371 Date: |
November 17, 2009 |
Current U.S.
Class: |
606/86R |
Current CPC
Class: |
A61B 17/7097 20130101;
A61B 17/7291 20130101; A61B 17/7098 20130101; A61B 17/1644
20130101; A61B 2017/00867 20130101; A61B 17/1642 20130101; A61B
17/72 20130101; A61B 17/742 20130101; A61B 17/1626 20130101; A61B
2217/005 20130101; A61B 17/7233 20130101; A61F 2310/00353 20130101;
A61B 17/7095 20130101; A61B 17/7266 20130101; A61B 17/1617
20130101; A61B 17/1633 20130101; A61B 17/1615 20130101; A61B
2017/1648 20130101; A61B 17/1631 20130101; A61F 2002/2832 20130101;
A61B 17/1668 20130101; A61B 17/164 20130101; A61B 17/7258 20130101;
A61B 90/39 20160201; A61B 17/1637 20130101; A61B 2090/036 20160201;
A61F 2002/2825 20130101; A61F 2002/30583 20130101; A61F 2210/0085
20130101 |
Class at
Publication: |
606/86.R |
International
Class: |
A61B 17/56 20060101
A61B017/56 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2007 |
IL |
181211 |
Apr 26, 2007 |
IL |
042607 |
Claims
1-45. (canceled)
46. A method of preventive surgery, comprising: (a) identifying a
long bone in need of strengthening; and (b) implanting a
strengthening implant in said bone through an aperture formed in
the bone.
47. A method according to claim 46, wherein said bone is a hip.
48. A method according to claim 46, wherein said bone is not
indicated as fractured by said identifying.
49. A method according to claim 46, wherein implanting comprises
binding at least two spaced apart reinforcing elements with a
binding material.
50. A method according to claim 46, wherein said strengthening
implant comprising a tension-resistant element.
51. A method according to claim 46, wherein said strengthening
implant comprising a bend-resistant element.
52. A method according to claim 49, comprising selecting a
personalized dimension for said implant for said bone.
53. A method according to claim 46, wherein said implant is
configured to rest against a cortex of said bone at one end and in
a middle section thereof.
54. A method according to claim 46, wherein identifying comprises
providing a patient with a problem in one limb and treating both
that limb and an opposing limb, by implantation of implants
therein.
55. A method of preventive surgery, comprising: (a) identifying a
long bone in need of strengthening; and (b) building, in situ, a
strengthening implant formed of a hardening material and at least
one reinforcing element, which reinforcing element is not adapted
to anchor in bone.
56. A method according to claim 55, wherein building comprises: (c)
forming a void in said bone; and (d) constructing said implant in
said void.
57. A method according to claim 56, wherein forming a void
comprises: (e) forming a channel; and (f) widening said
channel.
58. A method according to claim 57, wherein widening said channel
comprises cutting said channel using a cutting element.
59. A method according to claim 57, wherein forming a channel
comprises forming a curved channel.
60. A method according to claim 57, wherein forming a void
comprises forming a plurality of voids.
61. A method according to claim 57, wherein forming a void
comprises forming a void having a distal end not contacting and
within about 5 mm of a cortical bone.
62. A method according to claim 57, wherein constructing said
implant comprises inserting at least one tensile element into said
void and filling said void using cement.
63. A method according to claim 62, wherein inserting at least one
tensile element comprises inserting a bag into which said cement is
provided.
64. A method according to claim 62, wherein inserting at least one
tensile element comprises inserting a second bag into said bag.
65. A method according to claim 63, wherein filling said void
comprises eluting at least part of said cement out of said bag to
form inter-digitations.
66. A method according to claim 63, wherein filling said void
comprises eluting at least part of said cement out of said bag to
form at least one bulbous anchor section.
67. A method according to claim 63, wherein inserting at least one
tensile element, comprises inserting a plurality of tensile
elements into said bag.
68. A method according to claim 63, wherein inserting at least one
tensile element, comprises inserting a tensile element having at
least one end in a cortex.
69. A method according to claim 63, wherein inserting at least one
tensile element, comprises inserting said bag using a tensile
element.
70. A method according to claim 62, wherein inserting at least one
tensile element comprises inserting a bag into which said cement is
provided.
71. A method according to claim 55, wherein said method is
practiced by forming a hole having a maximal diameter of less than
5 mm.
72. A method according to claim 55, wherein said method is
practiced by forming a hole having a maximal diameter of less than
3 mm.
73-101. (canceled)
102. A method of constructing an implant comprising: (a) forming an
opening in cortical bone, which opening is less in diameter than a
30% of a diameter of said bone; (b) inserting at least three
non-expanding elements through said opening into said bone; (c)
completing said implant to have a diameter at least 3 times said
opening diameter.
103. A method according to claim 102, wherein said non-expanding
elements are elongate elements with a length to diameter ratio of
greater than 3 to 1.
Description
RELATED APPLICATIONS
[0001] The present application claims priority from IL Patent
Application No. 181211 filed on Feb. 7, 2007, and from IL Patent
application No. 182821 filed 26 Apr. 2007 the disclosures of which
are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to methods and devices for
strengthening of long bones, for example effective for preventing
fractures of bones.
BACKGROUND OF THE INVENTION
[0003] Hip fractures are a leading (indirect) cause of death in the
elderly. Typically, Osteoporosis, in which the inner trabecular
structure of the bone is destroyed, underlies the hip fracture.
Furthermore, it is known that a fracture in one hip is a reliable
indicator of danger of fracture in the other hip.
[0004] A typical bone structure is an outside of hard cortical bone
and an inside formed of softer bone, such as trabecular bone and/or
marrow or other non-structural tissue. Various blood vessels are
also provided in bone.
[0005] U.S. Pat. No. 6,679,890, the disclosure of which is
incorporated herein by reference, suggests hollowing out a portion
of a hip and injecting cement therein and then inserting a rigid
implant.
[0006] U.S. Pat. No. 4,755,184, the disclosure of which is
incorporated herein by reference, describes a bone implant
comprising a porous resorbable bag filled with cement.
[0007] U.S. Pat. No. 5,827,289, the disclosure of which is
incorporated herein by reference, suggests drilling a tunnel in a
bone, compacting bone surrounding the tunnel using a balloon and
then filling the tunnel with cement.
[0008] U.S. Pat. No. 6,425,923, the disclosure of which is
incorporated herein by reference, discloses a bag to be implanted
in a bone and filled with cement.
[0009] J Bone Joint Surg [Br] 2005; 87-B:1320-7, and J Bone Miner
Res 2000; 15:721-739 the disclosures of which are incorporated
herein by reference discusses the hip fracture problem in
general.
[0010] J Vasc Intery Radiol 2004; 15:121-126, the disclosure of
which is incorporated herein by reference, discusses various bone
cement compositions.
SUMMARY OF THE INVENTION
[0011] A broad aspect of some embodiments of the invention relates
to treating and/or preventing bone fractures, especially in long
bones. In some embodiments, a composite implant is constructed in
situ in the cortical bone and/or medullar portion of the bone. In
some embodiments, a metallic (or other) nail or screw is used.
[0012] In an exemplary embodiment of the invention, the method is
applied as a preventive measure, even though a bone to be treated
is not indicated as being fractured.
[0013] In an exemplary embodiment of the invention, a composite
implant is used which includes both one or more tensile elements
and a compressive element, such as hardened bone cement or an
adhesive material. In an exemplary embodiment of the invention, the
tensile elements are rods. In an exemplary embodiment of the
invention, a bag is provided enclosing most of the implant and/or
the rods. Optionally, the bag acts as a (optionally single) tensile
element.
[0014] In an exemplary embodiment of the invention, the implant is
constructed in situ via an aperture in the bone considerably
smaller in diameter than the final implant. In an exemplary
embodiment of the invention, a plurality of rods or other tensile
elements are inserted through the aperture to lie side by side, or
are otherwise adjacent, in the implant.
[0015] In an exemplary embodiment of the invention, the implant is
formulated and constructed to match needs of a specific patient,
for example, as estimated or as measured (e.g., pre-treatment or
during treatment). Optionally, a suggested formulation is provided
by a table or a circuitry based calculation
[0016] In an exemplary embodiment of the invention, the implant is
configured to have properties (e.g., one or more of density and
elastic modulus), similar to that of surrounding bone, for example,
trabecular and/or cortical bone.
[0017] In an exemplary embodiment of the invention, optionally, the
whole implant acts mainly as a strengthening element to the treated
bone and not mainly as a fixating element as in known bone
implants, while maintaining at least most natural strains
distributed in and/or through the treated bone. In an exemplary
embodiment of the invention, an implant for strengthening differs
from an implant for fixating, by providing substantially equal
engagement of cortical and/or trabecular bone along its length
(optionally excepting the cortical entrance). In an exemplary
embodiment of the invention, the bone engagement per unit length at
a distal end of the implant is less than a factor of 4, 3, 2, 1.5
or 1.3 greater than engagement per unit length along any tubular
section of 30% in length of the implant. Optionally or
alternatively, at most 60%, 40%, 30%, 20% of engagement is provided
by a distal end of the implant (e.g., a widening thereof).
[0018] In an exemplary embodiment of the invention, the implant is
positioned so that it leans on the cortex of the bone at least two
locations, for example, near an entrance to the bone and about
midway along the implant. Alternatively, the implant leans on
cortical bone at only one location, or even none.
[0019] In an exemplary embodiment of the invention, an implant
constructing kit is provided, which includes a tensile element
carrier adapted to carry tensile elements in to a bone void.
Optionally, there is included a bag holder which advances a bag
(and optionally holds it) into the void. Optionally or
alternatively, there is provided a bone drill optionally adapted to
form a cavity in bone greater than the diameter of the
aperture.
[0020] In an exemplary embodiment of the invention, a guide-wire
drill is used, in which a shaft-like element has a drilling tip
adapted to penetrate cortical bone and also suitable to attach at a
distal side to a mechanical rotational source (e.g., a drill
handle), while having a diameter suitable for use as a guide wire
for passing cannula and/or other tools over the drill, during a
procedure.
[0021] In an exemplary embodiment of the invention, the drill
includes a side-extending element which is adapted to form a void
in trabecular bone and/or remove cortical bone, when suitably
manipulated.
[0022] In some embodiments, flexible elements are used instead of
or in addition to rods, for example, yarn elements. In some
embodiments, no cement is used in the implant.
[0023] An aspect of some embodiments of the invention relates to
strengthening a bone using an implant comprising a mixture of
hardening material and tensile elements which contribute
significantly to the fracture and/or cracking resistance of the
bone and/or implant. In an exemplary embodiment of the invention,
the cement is disposed inside a container which acts as a tensile
element. In an exemplary embodiment of the invention, the tensile
elements and cement constitute a composite material. In an
exemplary embodiment of the invention, the tensile elements are
made of a composite or non-composite material, and they are
inserted into the bone, optionally in combination with cement.
Optionally or alternatively, the rods are inserted into a
container. In an exemplary embodiment of the invention, the
container provides only tensile strength. In an exemplary
embodiment of the invention, the combination of cement and tensile
elements provides stiffness and/or bending resistance equivalent to
bone (or better). Optionally, the implant is designed to resist
breakage at a degree of bending below that which will cause the
bone to break.
[0024] Optionally, the implant is indicated and/or used for
osteroporotic bone, metastatic bone, or other bone pathology that
may affect the strength of the bone. Optionally, the implant is
designed to allow the bone to receive stresses, for example,
stresses similar to natural bone stresses of that bone. Optionally,
the implant is used to fixate the bone while the bone heals,
following bone breakage, optionally for non-separating
fractures.
[0025] In an exemplary embodiment of the invention, when used for
fixating, a widening of the implant (e.g., cement and/or bag) is
provided at either end and/or distal end.
[0026] In an exemplary embodiment of the invention, when used for
fixating, the implant in inserted and filled with cement mainly at
its distal side. This cement is allowed to harden and then the
implant is retracted, optionally to reduce a fracture and/or
pre-tense the bone and then the rest of the cement is injected into
the implant.
[0027] In an exemplary embodiment of the invention, the implant
includes at least 20%, 30%, 45%, 60%, 80% or more or intermediate
percentages by volume of longitudinal tensile elements.
[0028] In an exemplary embodiment of the invention, the bone being
strengthened is a long bone, such as a leg bone (e.g., femur,
tibia, fibula) an arm bone (e.g. humerus, ulna, radius), foot and
hand phalanges or a clavicle, and the implant is elongate, for
example, with a width-length ratio of at least 1:3 or 1:4. In an
exemplary embodiment of the invention, an optional length of
implant for the femur is between 25 mm and 500 mm, optionally
between 50-100 mm, with optional diameter of between 1 mm and 20
mm, optionally 10 mm.
[0029] In an exemplary embodiment of the invention, the implant
comprises a flexible, substantially inelastic bag, optionally mesh,
as a container, filled with a bone fixing material (e.g., provided
as a fluid or paste and hardens to a solid, for example through a
setting process). Typical such fixing materials include but are not
limited to bone cement, such as PMMA, calcium phosphate, epoxy
and/or kryptonite. In an exemplary embodiment of the invention, the
bag comprises a tube closed off at a distal end thereof.
[0030] In an exemplary embodiment of the invention, the bag
functions to provide tensile strength and/or hold together the
cement and prevent cracking thereof. Optionally, some of the
tensile behavior is provided by the bag and some by additional
tensile elements. Optionally, some of the compressive behavior is
provided by the cement and some by additional elements. Optionally
50% of the bending resistance of the implant is provided by the
bag. Optionally or alternatively, 50% of the bending resistance
provide by the cement (e.g., with bag providing tensile resistance
and cement providing compressive resistance). In other embodiments,
the bag provides between 10%-80% of the bending resistance.
Alternatively the cement provides between 10%-80% of the bending
resistance. Optionally, the implant can withstand forces of greater
than 100 Kg, 200 Kg, 300 Kg, and/or impulses of greater than 100
Kg/sec, 200 Kg sec, 1000 Kg/sec or intermediate values, as applied
differentially to either side of the implant and perpendicular
thereto.
[0031] Optionally, the bag includes longitudinal fibers.
Optionally, the fibers are configured to yield a small amount in
the longitudinal direction. Alternatively or additionally, the bag
includes circumferential fibers. Optionally, the bag is preformed
to be curved. Alternatively or additionally, the bag is bent as
part of an implantation process.
[0032] In an exemplary embodiment of the invention, the bag element
contains a mesh having holes that are large enough to allow a small
amount of cement to escape the bag as it is filled, for example, to
provide inter-digitation with surrounding tissue such as trabecular
tissue. Alternatively, cement does not emerge from the bag, as for
example in cases where the mesh holes are too small with respect to
cement viscosity and/or particle sizes. Optionally, the mesh is
porous enough to allow air exit from the bag as it is filled.
[0033] In an exemplary embodiment of the invention, the bag is
configured to allow cement leakage (the term seepage is also used
herein) through it in some predefined parts, while it optionally
does not permit (or permits reduced amount of) cement leakage in
other parts. Optionally, the mesh holes are small enough so that
the act of filling the bag causes the bag to expand with enough
force to compact surrounding trabecular bone.
[0034] In an exemplary embodiment of the invention, the bag is
formed (e.g., woven) in a manner which defines specific pores.
Optionally, general pores are defined by the density of the weave,
of longitudinal and circumferential fibers. In an exemplary
embodiment of the invention, specific pores are formed by one or
more circumferential fibers being folded back at a pore, rather
than crossing the pore. Optionally, such a pore may have an axial
width of one, two, three or more circumferential fibers. Optionally
or alternatively, a similar arrangement is provided for
longitudinal fibers.
[0035] Optionally, a bio-absorbable cement is used and the pores
are selected so that bone can grow through them. Optionally, the
mesh is also bio-degradable/bio-absorbable.
[0036] In some embodiments of the invention, the implant includes
multiple layers of tensile elements, for example formed by
providing a container within a container. Optionally, the
containers are designed to maintain spacing between them, for
example are concentrically disposed. Alternatively or additionally,
an outer container is less permeable than an inner container.
[0037] In embodiments of the invention the implant is devoid of a
container such as a bag.
[0038] In some embodiments of the invention, the implant comprises
tensile elements, such as fibers or rods, embedded within the
cement, in embodiments in addition to a container and in
embodiments devoid of a container. Optionally, the rods are formed
of carbon-PEEK composite, carbon-PEKK composite and/or carbon-PMMA
composite.
[0039] In some embodiments, the container provides less than 10% of
tensile strength of the implant. Optionally, the mesh prevents
propagation of surface cracking.
[0040] In an exemplary embodiment of the invention, more than one
implant is introduced into bone. In an exemplary embodiment of the
invention, two containers are inserted into a proximal femur,
filled with rods of composite material (tensile elements), and
later filled with bone cement. In another embodiment, a plurality
of holes are drilled in bone, optionally in cortical bone, and
filled with cement and one or more tensile elements. In another
embodiment, in a hip, two crossing channels are defined, one along
femur and one along trochanter, such that an implant is formed
along the two lines.
[0041] In an exemplary embodiment of the invention, the implant is
used in bones in locations that experience forces addition to
compression forces, for example, experiencing tension, bending,
shear and/or rotation forces.
[0042] In an exemplary embodiment of the invention, the implant is
not strong enough to withstand typical forces that act on the bone,
without the support of the bone in an unbroken state thereof.
However the implant bears at least some of the forces applied to
the bone in which implanted.
[0043] A particular feature of some embodiments of the invention is
that stress is better distributed through the bone, due to better
integration of the implant with surrounding bone (e.g., due to
inter-digitations), better support of cortical bone (e.g., due to
cortical and/or trabecular resting points) and/or composite
material and design of implant. In an exemplary embodiment of the
invention, the cement support force distribution between the
tensile elements, for example, at least 50% of force coupling
between tensile elements is due to cement.
[0044] A broad aspect of some embodiments of the invention relates
to constructing an implant through an opening that is smaller than
the implant, where at least some of the load and/or tension bearing
elements are non-expanding. Optionally, a ratio of element length
to opening diameter is greater than 5:1, 7:1, 10:1 or intermediate
values. Optionally or alternatively, at least 3 substantially
identical elements are inserted. Optionally, the final implant has
a diameter greater by a factor of at least 2, 3, 4, 5 or more than
said opening.
[0045] In an exemplary embodiment of the invention, an implant
comprises a plurality of tensile elements, each with a diameter of
less than 20% of the diameter of the final implant and/or the
diameter of tensile parts thereof. During construction, the
elements are one after the other to lie side by side inside the
bone and at least partially define the size and/or mechanical
properties of the implant. Optionally, adhesion is provided by
injecting a bone cement. Optionally or alternatively, the tensile
are designed to interlock with each other, for example including
matching recesses and projections. Optionally or alternatively,
interconnection between the elements and surrounding matrix is
enhanced by the elements being formed with a material that bonds
well to the matrix, optionally the same material (e.g., PMMA based
rods with a PMMA matrix).
[0046] An aspect of some embodiments of the invention relates to
in-situ constructing of an implant. In an exemplary embodiment of
the invention, the implant is constructed by implanting a bag,
inserting a plurality of rods and injecting cement. Optionally, the
implant is completed by inserting a further rod. Optionally, the
last rod (or another rod) is long enough so that its proximal end
lies in a plane of the cortical bone. Optionally, the cement leaks
out of the bag to form inter-digitations with surrounding bone.
Optionally or alternatively, the cement leaks out of the bag as a
distal end point to form an anchoring section.
[0047] In an exemplary embodiment of the invention, a rod set is
provided, with a plurality of rods and one rod optionally longer
than other rods.
[0048] In an exemplary embodiment of the invention, a rod is
designed to that it slips past other rods, for example, rods
including a distal rounded end (optionally designed to not tear the
bag) and an inclined and optionally sharp proximal end, to support
slippage of the rounded end between two or more previously inserted
rods.
[0049] An aspect of some embodiments of the invention relates to a
composite implant which includes a plurality of materials therein
that interact to distribute forces along the implant and hold the
implant together. Optionally, tensile elements are not adapted to
anchor in bone. Alternatively or additionally, a hardening
material, such as adhesive, serves to interconnect the tensile
elements and/or transfer forces between them, alternatively or
additionally, to separating them. In an exemplary embodiment of the
invention, the implant is constructed in-situ. In a bag based
implant, a plurality of longitudinal elements of the bag, may each
act as a tensile element, independently of a cement holding
function of the bag.
[0050] An aspect of some embodiments of the invention relates to a
method of strengthening a long bone in which an elongate bone
strengthening implant(s) is inserted into the bone through an
opening made away from the bone ends, for example, the opening not
being within 25% of the length of the bone from either end.
Alternatively, the implant is inserted from an opening which is
closer to one of the bone ends. In an exemplary embodiment of the
invention, when a proximal femoral bone is treated, the opening is
located at the lateral side of the proximal femoral shaft, for
example slightly below the line of the lesser trochanter. In an
exemplary embodiment of the invention, the opening location is
selected to minimize damage and/or weakening of the bone, at least
with respect to certain failure modes of the bone. In an exemplary
embodiment of the invention, the implant is inserted along a path
drilled from the opening. In an exemplary embodiment of the
invention, the path is drilled without a guide wire.
[0051] In an exemplary embodiment of the invention, the implant
comprises a volume of cement, optionally enclosed in a container
such as a bag. Optionally, a container is an elongated bag
comprising longitudinally oriented fibers implanted so that the
longitudinally oriented fibers are substantially parallel to the
longitudinal axis of the bone section being strengthened.
[0052] In an exemplary embodiment of the invention, the implant is
implanted along an elongate formed channel which is optionally
curved to reach into a trochanter of a femur.
[0053] An aspect of some embodiments of the invention relates to a
kit for implant construction and provision, including a bag holder,
a tensile element carrier adapted to insert tensile elements into
the bag and a cement injector, all of which are optionally designed
to operate via a cannula. Optionally, a bag cutter is provided for
cutting or removing the bag from said holder after forming of the
implant.
[0054] In an exemplary embodiment of the invention, a tool used to
drill the channel is controlled using external forces to follow a
desired channel. Alternatively or additionally, the tool is
guidable (e.g., includes an orientable head) to follow a desired
path. Alternatively or additionally, the tool is guided by the
cortical layer of the bone. Alternatively or additionally, the tool
is guided by a K-wire, previously inserted into bone.
[0055] An aspect of some embodiments of the invention relates to a
drilling guidewire. In an exemplary embodiment of the invention,
the guide-wire has a substantially uniform shaft suitable for
delivering tools thereover into or to bone. In an exemplary
embodiment of the invention, the guide wire has a handle adapted to
fit into a drill in the same manner as a drill bit does.
[0056] An aspect of some embodiments of the invention relates to a
bone drill including both a forward bone drilling element and a
side drilling element. In an exemplary embodiment of the invention,
the side drilling element is selectively extendible so that said
bone drill can have a substantially uniform diameter along its
length when the side element is retracted. Optionally, the side
drilling element comprises a bone knife edge that is configured to
cut bone when said drill is rotated and retracted. In an
alternative embodiment, the side cutting element is replaced by a
water jet or jet of other material. Alternatively, the side cutting
element is strong enough to cut bone when the drill is rotated at a
low speed, such as 1 RPM, 10 RPM, 20 RPM or greater or intermediate
speeds. Optionally, for example while rotating, the side cutter is
moved in and out along the drills haft using a rail or lumen.
[0057] In an exemplary embodiment of the invention, the bone drill
is mounted on a shaft strong enough to be used for advancing the
bone drill through cortical bone.
[0058] In an exemplary embodiment of the invention, the drill head
drills when rotated in ether direction. In an exemplary embodiment
of the invention, the side element operates in either rotation
direction of the shaft and in forward and/or backwards axial
movements of the shaft.
[0059] In an exemplary embodiment of the invention, the side
element extends by the use of a pushing force guided along a lumen
or rail from outside the body. Optionally, a threading is provided
so a knob can be rotated and push the side element. Optionally, the
side element is the extension of a rod that reaches form the knob
to inside the body.
[0060] An aspect of some embodiments of the invention relates to a
drill adapted to create a curved path in a bone. In an exemplary
embodiment of the invention, the drill includes a head coupled to a
first, curved, elongate inner element contained within a second,
outer, tube which is stiffer than the inner element. In use, the
outer tube is advanced over the inner element when a part with a
first curvature (e.g., including a straight line) is desired. When
the outer tube is retracted, the curvature of the inner element
takes over and defines a curved path. Optionally, the head
comprises a burr on a wire and the inner element is a tube
enclosing the wire. Optionally, the size of opening created by the
head depends on the distance between the burr and the inner
element.
[0061] In another embodiment of the invention, a curved tube, for
example a tube having a "banana" shape, is used for drilling a
channel and/or implant insertion. In an exemplary embodiment of the
invention, the curved tube is made of nickel-titanium (Nitinol). In
another exemplary embodiment of the invention a burr, connected to
a rotator flexible shaft, is incorporated at the head of said tube.
In an exemplary embodiment of the invention, the curved tube is
guided, for example by a K-wire, optionally a curved K-wire.
[0062] In other embodiments of the invention, a straight channel is
made for implant insertion.
[0063] In an exemplary embodiment of the invention, said drill
incorporates water-jetting drilling and/or reaming capabilities,
e.g., drilling and/or reaming bone tissue by high speed water jets
with or without abrasive particles.
[0064] A broad aspect of some embodiments of the invention relates
to injecting exothermic-setting cement while minimizing damage to
healthy bone.
[0065] In an exemplary embodiment of the invention, the cement is
formulated to produce less heat, even if this reduces the strength
of the set cement. For example, the ratio of monomer to powder in
PMMA may be skewed so that there is less monomer than typical
and/or larger than usual beads may be used. In an exemplary
embodiment of the invention, the bending strength of the set cement
is allowed to be similar to that of bone or for example 20% less,
40% less or even 60% less, or less than 120% or intermediate
values. It is noted that the cement optionally serves to replace
trabecular bone. Optionally the completed implant has an elasticity
modulus of between 5-80 Gpa.
[0066] Optionally, reduction in strength is compensated for, at
least in part, by tensile implants.
[0067] In an exemplary embodiment of the invention, the cement, of
any type, is cooled during setting using an elongate cooling
element that remains in the cement as it sets, optionally serving
as a tensile element.
[0068] There is provided in accordance with an exemplary embodiment
of the invention, an elongate bone implant, comprising:
[0069] in-situ hardened material; and
[0070] a plurality of longitudinal tensile elements in contact with
said hardened material, which tensile elements have a greater
tensile strength than said hardened material,
[0071] wherein at least one of said tensile elements is not adapted
for anchoring to bone.
[0072] In an exemplary embodiment of the invention, said at least
two of said tensile elements are interlocked only by said hardened
material. Optionally or alternatively, forces are carried between
said at least two of said tensile elements only by said hardened
material. Optionally or alternatively, said at least two of said
tensile elements are spaced apart by said hardened material.
Optionally or alternatively, said plurality of tensile elements and
said hardened material act together as a composite material whose
mechanical properties are determined by the combination of the
hardened material and the tensile elements.
[0073] In an exemplary embodiment of the invention, said implant
has a length/diameter ratio of greater than 1:3.
[0074] In an exemplary embodiment of the invention, said implant is
configured to have an elasticity modulus greater than 5 Gpa.
Optionally or alternatively, said implant is configured to have
elasticity modulus less than 80 Gpa.
[0075] In an exemplary embodiment of the invention, said hardened
material comprises bone cement.
[0076] In an exemplary embodiment of the invention, said hardened
material comprises adhesive material.
[0077] In an exemplary embodiment of the invention, said
longitudinal tensile element comprises at least one bag surrounding
at least a portion of said hardened material. Optionally, said
longitudinal tensile element comprises nested bags. Optionally or
alternatively, said bag has an elongation of less than 10%.
Optionally or alternatively, said bag has a plurality of
longitudinal fibers. Optionally or alternatively, said bag has a
leading edge configured to hold a rod. Optionally or alternatively,
said bag has a plurality of general pores formed therein supporting
a seeping of said hardened material prior to hardening thereof.
Optionally, said seeping forms inter-digitations. Optionally or
alternatively, said bag has a plurality of specific pores formed
therein and having an average cross-section of at least 50% greater
than that of said general pores. Optionally or alternatively, said
bag has a first seepage area and a second seepage area, said first
area having an effective aperture area greater by at least 50% than
that of said second seepage area, said effective aperture area
calculated by adding up aperture areas and dividing by the seepage
area.
[0078] In an exemplary embodiment of the invention, said implant
does not include a bag enclosing at least 50% of said hardened
material.
[0079] In an exemplary embodiment of the invention, there is
provided a set of a plurality of spaced apart and substantially
axially parallel implants as described herein.
[0080] In an exemplary embodiment of the invention, said plurality
of tensile elements comprises at least one elongate element of a
diameter smaller than 50% than of an average diameter of said
implant, as measured along a long axis of said implant. Optionally,
said elongate element has a diameter of less than 4 mm. Optionally
or alternatively, said plurality of tensile element comprises at
least one elongate element of a diameter smaller than 1 mm.
Optionally or alternatively, said plurality of tensile elements
comprises at least one elongate element of a diameter smaller than
0.1 mm. Optionally or alternatively, said plurality of tensile
elements comprises at least one elongate element of a diameter
smaller than 0.01 mm. Optionally or alternatively, at least one of
said tensile element is flexible. Optionally or alternatively, at
least one of said tensile element is rigid and bend-resistant.
Optionally or alternatively, a first one of said tensile elements
has a shaped proximal end and a second one of said elements has a
shaped distal end, said shaped ends configured for sliding past
each other. Optionally or alternatively, the implant comprises a
plurality of elements filling at least 30% of said implant volume.
Optionally or alternatively, the implant comprises a plurality of
elements filling at most 80% of said implant volume. Optionally or
alternatively, the implant comprises at least one rigid bend
resisting element having a length of substantially an entire length
of said implant in bone. Optionally or alternatively, at least one
of said at least one elements includes a radio-opaque portion.
Optionally or alternatively, at least one of said at least one
elements has a geometry selected for encouraging engagement of said
hardened material during hardening thereof.
[0081] In an exemplary embodiment of the invention, said implant is
substantially straight.
[0082] In an exemplary embodiment of the invention, said implant is
curved to have a diameter of a smallest object of rotation thereof
greater than 200% of an average diameter by length of said
implant.
[0083] In an exemplary embodiment of the invention, the implant is
constituted to have a density within 50% of the density of
trabecular bone.
[0084] There is provided in accordance with an exemplary embodiment
of the invention, an implant kit comprising:
[0085] (a) an elongate sack;
[0086] (b) a plurality of tension rods having a length and diameter
suitable for fitting of at least 3 rods in said sack; and
[0087] (c) filler material precursors of an amount suitable to fill
said sack with said rods therein. Optionally, said sack has a
distal end including a reinforcement adapted to receive a distal
end of at least one of said rods. Optionally or alternatively, at
least one of said rods is longer than others of said rods by at
least 5% of an average rod length. Optionally or alternatively, at
least one of said rods is longer than others of said rods by at
least 5 mm. Optionally or alternatively, said sack is perforated to
support a seepage of said filler material over at least a portion
of said bag. Optionally or alternatively, said sack is additionally
perforated at a distal end thereof to support the formation of a
bulb of filler material thereat. Optionally or alternatively, each
of said rods has a diameter smaller than 4 mm. Optionally or
alternatively, a first one of said rods has a shaped proximal end
and a second one of said rods has a shaped distal end, said shaped
ends configured for sliding past each other.
[0088] There is provided in accordance with an exemplary embodiment
of the invention, a method of preventive surgery, comprising:
[0089] (a) identifying a long bone in need of strengthening;
and
[0090] (b) implanting a strengthening implant in said bone through
an aperture formed in the bone. Optionally, said bone is a hip.
Optionally or alternatively, said bone is not indicated as
fractured by said identifying. Optionally or alternatively,
implanting comprises binding at least two spaced apart reinforcing
elements with a binding material. Optionally or alternatively, said
strengthening implant comprising a tension-resistant element.
Optionally or alternatively, said strengthening implant comprising
a bend-resistant element. Optionally or alternatively, the method
comprises selecting a personalized dimension for said implant for
said bone. Optionally or alternatively, said implant is configured
to rest against a cortex of said bone at one end and in a middle
section thereof. Optionally or alternatively, identifying comprises
providing a patient with a problem in one limb and treating both
that limb and an opposing limb, by implantation of implants
therein.
[0091] There is provided in accordance with an exemplary embodiment
of the invention, a method of preventive surgery, comprising:
[0092] (a) identifying a long bone in need of strengthening;
and
[0093] (b) building, in situ, a strengthening implant formed of a
hardening material and at least one reinforcing element, which
reinforcing element is not adapted to anchor in bone.
[0094] In an exemplary embodiment of the invention, building
comprises:
[0095] (c) forming a void in said bone; and
[0096] (d) constructing said implant in said void.
[0097] Optionally, forming a void comprises:
[0098] (e) forming a channel; and
[0099] (f) widening said channel.
[0100] Optionally, widening said channel comprises cutting said
channel using a cutting element. Optionally or alternatively,
forming a channel comprises forming a curved channel.
[0101] In an exemplary embodiment of the invention, forming a void
comprises forming a plurality of voids. Optionally or
alternatively, forming a void comprises forming a void having a
distal end not contacting and within about 5 mm of a cortical bone.
Optionally or alternatively, constructing said implant comprises
inserting at least one tensile element into said void and filling
said void using cement. Optionally, inserting at least one tensile
element comprises inserting a bag into which said cement is
provided. Optionally or alternatively, inserting at least one
tensile element comprises inserting a second bag into said bag.
Optionally, filling said void comprises eluting at least part of
said cement out of said bag to form inter-digitations. Optionally
or alternatively, filling said void comprises eluting at least part
of said cement out of said bag to form at least one bulbous anchor
section. Optionally or alternatively, inserting at least one
tensile element, comprises inserting a plurality of tensile
elements into said bag. Optionally or alternatively, inserting at
least one tensile element, comprises inserting a tensile element
having at least one end in a cortex. Optionally or alternatively,
inserting at least one tensile element, comprises inserting said
bag using a tensile element.
[0102] In an exemplary embodiment of the invention, inserting at
least one tensile element comprises inserting a bag into which said
cement is provided.
[0103] In an exemplary embodiment of the invention, said method is
practiced by forming a hole having a maximal diameter of less than
5 mm. Optionally or alternatively, said method is practiced by
forming a hole having a maximal diameter of less than 3 mm.
[0104] There is provided in accordance with an exemplary embodiment
of the invention, a kit for constructing an implant in situ,
comprising:
[0105] (a) a void former adapted to form an elongate void in
bone;
[0106] (b) a carrier configured to provide at least one elongated
structural element into said void; and
[0107] (c) a filler material injector configured to provide filler
material into said void.
[0108] Optionally, said at least one elongated element is a
tension-resistant element. Optionally or alternatively, said at
least one elongated element is a bend-resistant element. Optionally
or alternatively, said carrier is configured to push a longitudinal
element into said void. Optionally, the kit comprises a sack
carrier adapted to insert a sack into said void. Optionally, said
tensile element carrier is configured to match said bag carrier and
said bag in length so that it pushes said element to an end of said
bag.
[0109] In an exemplary embodiment of the invention, said tensile
element carrier is configured to release a tensile element into
said void as said tensile element carrier is retracted.
[0110] In an exemplary embodiment of the invention, said void
former is bendible.
[0111] In an exemplary embodiment of the invention, said void
former comprises a narrow void former and a void widener.
Optionally, said void widener comprises a cutting element.
[0112] In an exemplary embodiment of the invention, the kit
comprises a cannula adapted for bone access and engaging a bone
cortex and sized to pass the intrabody portions of said void former
and said tensile element carrier.
[0113] In an exemplary embodiment of the invention, the kit
comprises a bag and a plurality of tensile elements in the form of
rods.
[0114] There is provided in accordance with an exemplary embodiment
of the invention, a device for disposing longitudinal rods within a
cavity in bone, comprising:
[0115] (a) a handle;
[0116] (b) a shaft adapted to be inserted into a bone cavity
through a cannula; and
[0117] (c) a rod holder formed at least at a distal end of said
shaft and adapted to hold a rod.
[0118] Optionally, said rod holder has an outer diameter along most
of said shaft which is less than 20% greater than a diameter of a
rod it is adapted to hold. Optionally or alternatively, said device
is adapted to dispose rods with a diameter of less than 5 mm.
[0119] In an exemplary embodiment of the invention, the carrier
comprises a pusher adapted to release said rod from said rod holder
by pushing against a proximal end of said rod.
[0120] In an exemplary embodiment of the invention, the carrier
comprises a magazine holding at least three rods.
[0121] There is provided in accordance with an exemplary embodiment
of the invention, a bone drill comprising:
[0122] (a) a shaft with a substantially uniform diameter and
adapted for cannulated access to bone and including a distal end
configured for attachment to a motorized drill handle;
[0123] (b) a bone drilling head at a distal tip of the shaft and
adapted for drilling into both cortical bone and trabecular
bone,
[0124] wherein said drill has a maximal diameter within 10% of an
average diameter of said drill, by length.
[0125] Optionally, said shaft is rigid. Optionally or
alternatively, the drill comprises:
[0126] (c) at least a side extending element configured to
selectively extend in a direction perpendicular to said shaft and
stiff enough when extended to cut trabecular bone at a rotation
speed below 20 RPM. Optionally, said side-extending element
comprises a wire. Optionally or alternatively, said side-extending
element comprises an edged cutting element. Optionally or
alternatively, said side-extending element is extended along a
linear passage in said shaft. Optionally, said side-extending
element is extended by a pushing force applied from outside a body.
Optionally or alternatively, the drill comprises a shield
preventing bone chips from entering in to said passage.
[0127] There is provided in accordance with an exemplary embodiment
of the invention, a long bone implant comprising:
[0128] (a) a plurality of stiff rods; and
[0129] (b) a binding material hardened in-situ,
[0130] wherein at least one of said rods has a length of more than
50% of a length of said implant
[0131] Optionally, said implant has inner shear resistance that is
substantially equivalent to that of cancellous bone. Optionally or
alternatively, at least two of said rods are spaced apart by said
binding material. Optionally or alternatively, said implant further
comprising a meshed element through which said binding material
seeps.
[0132] There is provided in accordance with an exemplary embodiment
of the invention, a method of constructing an implant
comprising:
[0133] (a) forming an opening in cortical bone, which opening is
less in diameter than a 30% of a diameter of said bone;
[0134] (b) inserting at least three non-expanding elements through
said opening into said bone;
[0135] (c) completing said implant to have a diameter at least 3
times said opening diameter.
[0136] In an exemplary embodiment of the invention, said
non-expanding elements are elongate elements with a length to
diameter ratio of greater than 3 to 1.
[0137] There is provided in accordance with an exemplary embodiment
of the invention a method of strengthening a bone, comprising
providing at least one implant which lays mostly inside a cortical
portion of said bone.
[0138] There is provided in accordance with an exemplary embodiment
of the invention a method of strengthening a bone, comprising
providing at least one implant into said bone, said implant resting
at one end thereof against at least one void in cortical bone and
resting at a section within a middle 50% of length of said implant
inside bone, against an inside surface of cortical bone.
Optionally, the method includes setting at least one resting place
of said implant against bone by eluting cement out of said
implant.
[0139] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, suitable methods and materials are described below. In
case of conflict, the patent specification, including definitions,
will control. In addition, the materials, methods, and examples are
illustrative only and not intended to be limiting.
[0140] As used herein, the terms "comprising" and "including" or
grammatical variants thereof are to be taken as specifying the
stated features, integers, steps or components but do not preclude
the addition of one or more additional features, integers, steps,
components or groups thereof. This term encompasses the terms
"consisting of" and "consisting essentially of".
[0141] The phrase "consisting essentially of" or grammatical
variants thereof when used herein are to be taken as specifying the
stated features, integers, steps or components but do not preclude
the addition of one or more additional features, integers, steps,
components or groups thereof but only if the additional features,
integers, steps, components or groups thereof do not materially
alter the basic and novel characteristics of the claimed
composition, device or method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0142] In the drawings which follow, identical structures, elements
or parts that appear in more than one drawing are generally labeled
with the same numeral in all the drawings in which they appear.
Dimensions of components and features shown in the drawings are
chosen for convenience and clarity of presentation and are not
necessarily shown to scale.
[0143] FIG. 1 is a flowchart of a method of strengthening a bone to
prevent fractures, in accordance with an exemplary embodiment of
the invention;
[0144] FIGS. 2A-2J is a series of figures showing a process of
forming a bore in a hip bone and various configurations thereof, in
accordance with an exemplary embodiment of the invention;
[0145] FIGS. 2K-2M is a series of figures showing examples of
implant locations in accordance with an exemplary embodiment of the
invention;
[0146] FIGS. 3A and 3B illustrate a distal end of a drilling device
used in FIG. 2, in a straight and in a curved state, in accordance
with an exemplary embodiment of the invention;
[0147] FIGS. 4A-4D depict axial cross sections of bones treated in
accordance with the teachings of the present invention so that a
cross section of embodiments of implants of the present invention
are apparent;
[0148] FIGS. 5A-5B depict longitudinal cross sections of bones
treated in accordance with the teachings of the present invention
so that a cross section of embodiments of implants of the present
invention are apparent;
[0149] FIGS. 6A-6B depict an axial cross section and a longitudinal
cross section of a bone treated in accordance with the teachings of
the present invention having tensile elements implanted inside the
bone;
[0150] FIG. 7A illustrates a cross section view of a longitudinal
implant, in accordance with an exemplary embodiment of the
invention;
[0151] FIG. 7B illustrates a cross section view of a bone cavity
occupied by a composite implant comprising a plurality of
longitudinal elements and binding material, in accordance with an
exemplary embodiment of the invention;
[0152] FIGS. 8A-8D illustrate cross sections of several drilling
heads which incorporate water jet techniques, in accordance with an
exemplary embodiment of the invention;
[0153] FIGS. 9A-9B illustrate cross sections of an inflatable
drilling head, in accordance with an exemplary embodiment of the
invention;
[0154] FIG. 10A is a flowchart of a method of composite bone
implant construction and implantation, in accordance with an
exemplary embodiment of the invention;
[0155] FIG. 10B is a cross-sectional view of a composite implant in
a bone, in accordance with an exemplary embodiment of the
invention;
[0156] FIGS. 10C-10I illustrate acts in the method of FIG. 10A,
using the tools of FIGS. 11-19, in accordance with an exemplary
embodiment of the invention;
[0157] FIGS. 11-19 illustrate components of a bone implant kit
usable for the method of FIG. 10A, in accordance with an exemplary
embodiment of the invention;
[0158] FIG. 11 illustrates a bone access cannula, in accordance
with an exemplary embodiment of the invention;
[0159] FIGS. 12A-12E illustrate a bone drill, in accordance with an
exemplary embodiment of the invention;
[0160] FIG. 13 illustrates the bone drill of FIGS. 12A-12E mounted
in the bone access cannula of FIG. 11, in accordance with an
exemplary embodiment of the invention;
[0161] FIG. 14 illustrates a stylet, in accordance with an
exemplary embodiment of the invention;
[0162] FIG. 15 illustrates a cement delivery cannula with the
stylet of FIG. 14 mounted therein, in accordance with an exemplary
embodiment of the invention;
[0163] FIGS. 16A-16C illustrate a bag holder in accordance with an
exemplary embodiment of the invention;
[0164] FIG. 17 illustrates the stylet of FIG. 14, mounted in the
cement delivery cannula of FIG. 15, mounted in the bag holder of
FIGS. 16A-16C, all mounted in the bone access cannula of FIG. 11,
in accordance with an exemplary embodiment of the invention;
[0165] FIGS. 18A-18B illustrate a rod carrier, in accordance with
an exemplary embodiment of the invention;
[0166] FIG. 19 illustrates the rod carrier of FIGS. 18A-18B,
mounted in the bag holder of FIGS. 16A-16C, all mounted in the bone
access cannula of FIG. 11, in accordance with an exemplary
embodiment of the invention;
[0167] FIGS. 20A and 20B illustrate an alternative side drill
extension, in accordance with an exemplary embodiment of the
invention;
[0168] FIG. 20C-20E illustrate another alternative side drill
extension, in accordance with an exemplary embodiment of the
invention;
[0169] FIG. 21A-21B illustrate multi-rod pushers, in accordance
with exemplary embodiments of the invention;
[0170] FIG. 22 illustrates a multi-tool system, in accordance with
an exemplary embodiment of the invention;
[0171] FIGS. 23A and 23B illustrate tensile rods, in accordance
with exemplary embodiments of the invention;
[0172] FIG. 24A-24D illustrate bag attachment methods in accordance
with an exemplary embodiment of the invention;
[0173] FIG. 25 illustrates a sleeve cutting tool, in accordance
with an exemplary embodiment of the invention; and
[0174] FIG. 26 illustrates a weave of a bag including a pore, in
accordance with an exemplary embodiment of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
Overview
[0175] FIG. 1 is a flowchart 100 of a method of strengthening a
bone, for example to prevent fractures, in accordance with an
exemplary embodiment of the invention. In brief, the method
includes identifying a need (102), forming a channel in the bone
(104), inserting an implant and/or a container (106), optional
inflating the container using cement (108), optional repeating or
otherwise manipulating the container (110) and completing the
procedure (112).
Exemplary Prophylactic Treatment
[0176] The method schematically depicted in FIG. 1 is explained for
a specific prophylactic treatment of a non-fractured femur 10 as
depicted in FIGS. 2A-2M. However, the treatment is not limited for
preventive purposes, and may also be used for the treatment of
broken bones. In these figures is described the implantation of an
implant 12 of the some embodiments of the present invention. FIG.
2I depicts the implant fully assembled and deployed in a
longitudinal channel 11 running through femur 10. This channel is
optionally formed using a drilling device 18 depicted in FIGS. 3A
and 3B. Implant 12 optionally comprises an elongated fiber bag 14
as a tensile element that is a container filled with a cement 16
such as PMMA
Identify Need
[0177] In 102, a need is identified for treating a bone. Typical
identifying of a need includes, for example, one or more of
determining a sufficiently high likelihood of a fracture of a
specific long bone, for example due to a history of a fracture in
the bone, history of fracture of a same bone on the other side of
the body, identification of microfractures and cracks in a bone and
osteoporosis. In FIG. 2, femur 10 is not fractured but the opposing
femur of the same patient was previously fractured at the femoral
neck 20.
Form Channel
[0178] At 104, a longitudinal channel 11 is formed substantially in
parallel to shaft 22 of femur 10 extending up into femoral neck 20.
Alternatively, a curved or straight channel is formed, where its
opening is located at a higher point in the femur shaft (i.e.,
closer to the bone proximal end).
[0179] An insertion hole 24 (between about 2 mm and about 15 mm in
diameter) is drilled through the compact tissue constituting the
wall of shaft 22 into the medullary cavity 26 of femur 10, for
example, using a standard rigid drill 28 in accordance with methods
known in the art. The location where insertion hole 24 is made is
optionally distal from femoral neck 20 and through compact tissue.
This may reduce pain, complications and/or reduce further weakening
of regions in proximity to femoral neck 20.
[0180] Channels in the soft tissue surrounding the bone is
optionally made using minimally invasive methods (e.g., small hole
of several mm), such as using drill 28, or using an open cut.
[0181] As noted above, in an embodiment of the invention depicted
in FIG. 2, a suitable longitudinal channel 11 is formed in femur 10
with the help of a drilling device 18 depicted in FIGS. 3A and 3B.
In some embodiments, the channel is along the trochanter.
[0182] A first exemplary drilling device 18 is substantially
analogous to a catheter type device. In FIGS. 3A and 3B is depicted
only the distal end of drilling device 18 which comprises an outer
guide tube 30 through which bore runs inner drill guide tube 32
through which bore runs a rotation wire 34 tipped with an
excavation component, for example, a standard bone drilling burr
36. In an exemplary embodiment of the invention, inner tube 32 is
relatively flexible (compared to outer guide tube 30, and in
embodiments elastic and is configured to curve at the tip to one
side. Rotation wire 34 is functionally associated with a rotator
such as a high speed electrical motor known in the art of surgical
drills. In an alternative exemplary embodiment of the invention
(not shown), tube 30 has a tilting distal end which can be
manipulated from outside the body (via tube 30 proximal end), such
that the operator can choose between a first straight position and
a second tilted position, or vise versa. Optionally, the preferred
tilt angle can also be determined and carried out. Optionally, pull
wires are used to effect such manipulations
[0183] In embodiments, guidance of a drilling device is performed
in other manners, for example using magnetic guidance to
magnetically manipulate the drilling tip (which may be selectively
made of a ferromagnetic material or act as an electromagnet).
[0184] In embodiments, a drilling device such as drilling device 18
is configured to aspirate material excavated by an excavation
component, for example by being functionally associating with a
pump or another vacuum source.
[0185] In embodiments, an excavation component constitutes, in
addition to or instead of a burr such as burr 36, a different
excavation component. Typical such excavation components include
but are not limited to hard piercing members (optionally configured
to tunnel through the tissue in a medullary cavity and/or
trabecular bone but not cortical bone), ultrasonic transducers,
electro ablators, drills, reamers, fluid jets, morsolaters,
electrical ablators, vibrating needles and/or laser drilling
devices. In embodiments, an excavation element, such as a burr are
configured to have a variable configuration (e.g. by controlling
the axial distance of burr 36 from inner tube 32) to change the
diameter of a channel made with the excavation element. Typically,
the diameter of a longitudinal channel 11 excavated in a femur is
not less than 2 mm, not less than 3 mm, not less than 4 mm, not
less than 5 mm, not less than 6 mm and even not less than 8 mm or
intermediate values.
[0186] In an exemplary embodiment of the invention, for forming
longitudinal channel 11, burr 36 of drilling device 18 is inserted
through insertion hole 24 into medullary cavity 26 of femur 10 when
inner tube 32 is substantially entirely within outer tube 30 so
that burr 36 is substantially near the end of outer tube 30, as
depicted in FIG. 3A. Inner tube 32 is pushed outwards from outer
tube 30. No longer constrained by the relatively rigid outer tube
30, inner tube 32 curves upwards inside medullary cavity 26 towards
femoral neck 20, substantially as depicted in FIG. 3B.
[0187] The rotator (e.g., motor or manual handle) functionally
associated with rotation wire 34 is optionally activated so as to
rotate rotation wire 34 and thus burr 36. As burr 36 rotates, inner
tube 32 is pushed outwards from outer tube 30 to advance upwards
inside against the inner wall of compact tissue, defining medullary
cavity 26 and excavating tissue so as to define longitudinal
channel 11.
[0188] Optionally, outer tube 30 and/or inner tube 32 and/or
rotation wire 34 are coupled on their proximal end to an electrical
or a mechanical drill, which optionally provides rotation and/or
hammer impact (not shown). Optionally, wire 34 is not rotated but
rather pulled and pushed with a desired force and/or frequency.
[0189] In an exemplary embodiment of the invention, when a
sufficient length of longitudinal cavity has been excavated (e.g.,
as determined by an operator, optionally using x-ray imaging), for
example where further excavation may lead to an improperly shaped
longitudinal channel, outer tube 30 is advanced inwards so as to
support and straighten inner tube 32, see FIG. 2E. In embodiments,
inner tube 32 functions as a guide for outer tube 30. In
embodiments, during extension of inner tube 32 by a small amount
(e.g., 1-2 cm) from outer tube 30, inner tube 32 is straight and
can thus be used to excavate a straight part of longitudinal
channel 11 while a greater extension (e.g., greater than 3 cm)
leads to substantial curvature of inner tube 32.
[0190] When longitudinal channel 11 has been excavated to near
femoral neck 20 (e.g., near the intertrochanteric line), inner tube
32 is pushed distally out from outer tube 30 so as to curve into
femoral neck 20, preferably close to the axis of the femoral neck,
see FIG. 2F.
[0191] Excavation of tissue in femoral neck 20 is continued as
described above until longitudinal channel 11 is sufficiently long.
In the embodiment depicted in FIG. 2G, longitudinal channel 11
extends from insertion hole 24 inside shaft 22 until into femoral
neck 20.
Insert Implant
[0192] At 106, tensile elements are inserted into longitudinal
channel 11, in FIG. 2 a container which is substantially a bag 14.
In a typical embodiments, a bag 14 is of knit 25 Dtex Dyneema.RTM.
(vide infra) with holes of about 0.04 mm.sup.2 and a maximal
inflated diameter 20% greater than that of longitudinal channel 11.
While outer tube 30 of drilling device 18 is substantially
maintained in place, inner tube 32 is withdrawn together with
rotation wire 34 and burr 36, see FIG. 2H. Elongated bag 14
(optionally knotted at the top) is placed over the blunted tip of a
flexible inflation and guide tube 38 and pushed upwards to the
distal end of longitudinal channel 11 with the help of inflation
and guide tube 38.
Fill Implant
[0193] At 108, bag 14 is filled with cement. When elongated bag 14
contacts the end of longitudinal channel 11, cement such as PMMA is
injected slowly through inflation and guide tube 38. Stepwise or
simultaneously, a portion of cement 16 is injected and inflation
and guide tube 38 is withdrawn so that elongated bag 14 fills out
and compresses against the tissue defining the walls of
longitudinal channel 11. In embodiments, the mass of partially set
cement maintains bag 14 in place as inflation and guide tube 38 is
withdrawn. Alternatively, a tensile element such as bag 14 is
maintained in place with the help of an anchoring component, for
example, as described below. In embodiments where setting of cement
16 may release heat, the rate of cement injection is optionally
slow enough so as not to cause substantial damage or discomfort to
the subject being treated. In some embodiments, an inflation and
guide tube 38 is configured to assist in removing heat generated by
setting cement, for example by including a channel for the
transport of cooling fluid. When sufficient cement 16 has been
injected into bag 14, inflation and guide tube 38 is withdrawn from
femur 10 out through insertion hole 24.
[0194] In embodiments, cement 16 is optionally injected into bag 14
at a pressure sufficient to compact and/or inter-digitate
surrounding trabecular bone. In embodiments, cement 16 is
optionally injected at such a pressure into bag 14, and the walls
of bag 14 are such that cement leaks through portions of the walls
of bag 14 so as to achieve interdigitation with bone tissue.
[0195] In typical femoral embodiments, an inflated diameter of a
container such as a bag is between about 10 mm and 20 mm, for
example 15 mm. It is important to note that although in FIGS. 4A-4D
bag 14 fills only a small portion of the cross section of the
medullary cavity of femur 10, in some embodiments a bag 14 (or
several bags) fills a majority of a the medullary cavity, or the
medullary cavity in its entirety.
Repeat and Manipulate
[0196] In some embodiments, the steps above are repeated, for
example to insert an additional bag 14 in a different femur or in
the same femur as depicted in FIG. 4B.
[0197] In an exemplary embodiment of the invention, the implant is
manipulated, for example, by insertion of tensile elements thereto,
for example, as described below.
Complete Procedure
[0198] At 112, the procedure is completed. In an exemplary
embodiment of the invention, the proximal end of bag 14 trimmed
(optionally as described below), remnants pushed into insertion
hole 24, and/or insertion hole 24 blocked with standard bone
filling paste such manufactured by Exactech, Inc (Gainseville,
Fla., USA).
Tensile Elements
[0199] In some embodiment, such as discussed above, the tensile
elements of the implant are exclusively the filaments that
constitute bag 14, as depicted in cross section in axial FIG.
4A.
[0200] In some embodiments, additional tensile elements are
introduced, for example, contained within bag 14. In some
embodiments, the added tensile elements are threads, rods and/or
additional bags.
Multiple Bag Layers
[0201] In some embodiments, a bag 14 is a multilayer bag, including
multiple layers of material defining the walls of bag 14.
[0202] In some embodiments, the additional tensile elements are one
or more additional bags 40 similar to bag 14, but optionally of
smaller maximal diameter and optionally with larger perforations
through the walls of the bag. Subsequent to insertion of bag 14 and
injection (in some embodiments before and in some embodiments
after) of a portion of cement, inflation and guide tube 38 is
withdrawn and used to insert additional bags 40 inside bag 14. In
some embodiments additional (an additional 1, 2, 3, 4 or even more)
bags 40 are inserted coaxially to bag 14, see FIG. 4C. In some
embodiments additional bags 40 are inserted collinear but not
coaxial to bag 14, see FIG. 4D. As noted, in FIGS. 4C and 4D bag 14
can fill only a small portion of the cross section of the medullary
cavity of femur 10, in embodiments a bag 14 fills a majority of a
the medullary cavity, or the medullary cavity in its entirety. In
some embodiments the bags are inserted side by side inside bag 14.
In some embodiments, a strip or other form is used instead of a
bag, with a distal end of the strip being adapted for being pushed
by a stylet, for example, including a cup or a loop.
[0203] Inflation and guide tube 38 is optionally used to push the
end of additional bags 40 (optionally knotted or provided with some
other anchoring feature) into the partially set cement or is used
to inject an additional anchoring portion of cement 16 as depicted
in longitudinal cross section in FIG. 5A. When all desired
additional bags 40 have been placed inside longitudinal channel 11,
cement 16 is injected substantially as described above. In
embodiments when at least one additional bag 40 is placed inside a
bag 14, cement 16 is optionally injected so as to flow through
perforations in the wall of the bag to also fill up bag 14. Once
sufficient cement has been injected to fill the bags, the procedure
is completed substantially as described above.
[0204] In embodiments of the present invention including multiple
bags 14 and 40, the bags are optionally interconnected, for example
with filaments or the like to enforce a desired spacing. In some
embodiments, the bags are substantially similar. In other
embodiments at least some of the bags are different, for example
provided with different sized perforations in the walls or
including filaments of different strengths.
[0205] In some embodiments of the invention, limiting the maximal
extent of inflation of a bag (e.g., 14 or 40) allows, by injecting
a certain amount of relatively viscous cement, to pretension the
tensile elements, increasing the strength of an implant of the
present invention. Optionally or alternatively, over injection of
cement causes leakage of cement out of the bag. Optionally however,
the cement is viscous enough or includes some particles so that
some pre-tensioning of the bag is provided as well.
[0206] Optionally, in a multi-bag embodiment, at least one of the
bags (e.g., an outer or inner one) has pores and another bag does
not. Optionally, the pores of different bags are positioned to
match up or not match up, depending on the implant design.
[0207] In an exemplary embodiment of the invention, at least some
of the fibers, for example, that form the bag and/or tensile
elements, are formed of a material and/or structure that expands.
Such expansion, can be, for example, contact with fluid (e.g.,
absorption), heat and/or as a result of a chemical reaction with
cement.
Non-Bag Tensile Elements
[0208] In some embodiments, the tensile elements are one or more
elongated tensile elements, e.g., filaments, monofilaments and
multifilaments such as fibers, cables, threads, wires, strings and
optionally multifilament tensile elements such as yarns, braids,
crochets and knits having a certain limited, degree of axial
extensibility when embedded within cement 16 contained within bag
14. Optionally, as described below in greater detail, rods are
used.
[0209] In an exemplary embodiment of the invention, the
extensibility (if any) of the tensile elements is matched with that
of the cement to prevent cracking of the cement when they extend.
Placement of such tensile elements 42 is optionally substantially
as described above for additional bags and may be simplified by the
addition of an anchoring element 44 such as an eyelet, a knot or
general broadening which is conveniently pushed into the hardening
cement as depicted in FIG. 5B. Once sufficient cement has been
injected to fill a bag 14 and to fill longitudinal channel 11, the
procedure is completed substantially as described above. When
tensile elements are pushed (or advanced and then released) into a
longitudinal channel 11, for example with a blunt needle or a rod,
the blunt needle or rod may have a smaller diameter than a guide
tube as such a needle or rod is optionally not configured for
injection of cement. In an exemplary embodiment of the invention,
the needle encloses the element and is inserted into the bag or
implant, optionally to the bag's end. Then, the tensile elements
are pushed out, for example, using a pushing rod coaxial with the
needle or held in place thus while the needle is retracted.
Optionally, the ends of previously inserted fibers remain outside
the body (and are held) so that the insertion of the needle does
not push in the fibers
[0210] Generally, in a situation where sufficient cement has
sufficiently hardened to anchor an additional tensile element, or
in embodiments employing an anchoring component, see below, the
tensile element is optionally pulled so as to pretense the tensile
element. The cement is allowed to harden so as to maintain the
tensile element in a pre-tensioned state.
[0211] Optionally, flexible tension elements include a hook or
expanding anchor (e.g., shape memory or super-elastic element) at
their tip, to prevent their retraction with the needle which
inserts them.
[0212] In some embodiments of the invention (FIG. 7), the implant
comprises elongated tensile elements, such as rods, which are made
of composite material that includes longitudinal, continuous fibers
"glued" together or encapsulated within polymer matrix (e.g., PEEK,
PMMA, PEKK epoxy, bone cement, Silicone, Polyurethane). An optional
not binding exemplary implant 60 cross section is schematically
illustrated in FIG. 7A. Elongated rods 51 are relative parallel
disposed within a container 62. Bone cement 61 fills the gaps among
and around said rods 51. FIG. 7B illustrates a single rod 51,
comprising plurality of elongated fibers 52 (for example made of
carbon) attached to each other by-/embedded within a matrix 53
(e.g., a polymer such as PEEK, PMMA, PEKK).
[0213] In an exemplary embodiment of the invention, the elongated
fibers can be one or any combination of the followings: carbon rods
or fibers, aramid yarns (e.g. Kevlar or Dyneema), Nylon fibers,
PMMA fibers, metal fibers (e.g., Stainless Steel, Titanium,
Aluminum, Tungsten alloys), nano tubes. One not binding exemplary
tensile element raw material can be the biocompatible ENDOLIGN.TM.
composite material (from Invibio Biomaterial Solution, UK) which is
composed of continuous carbon fibers in a PEEK-OPTIMA.RTM. polymer
matrix. While in some embodiments the elements are composite, in
others they are not, for example, being made of metal or PEKK.
[0214] In an exemplary embodiment of the invention, the rods may be
inserted into a container or may be delivered into bare bone (i.e.,
no container). Optionally, a channel is created (e.g., drilled) in
the bone (optionally in the cortical bone only and parallel to its
surface) prior to implant insertion (in a similar manner as
described above and below). Optionally, the rods are inserted
one-by-one, or optionally one per hole. Optionally, once a desired
quantity of said rods are introduced into bone, bone cement (e.g.,
PMMA, calcium phosphate, calcium sulfate) is introduced into the
container (where container is used) or into bone (when container is
not used) to fill the gaps between and around the rods. The
container (if used) can be permeable (e.g., a bag/mesh),
impermeable (e.g., a sealed balloon-like container), or
semi-permeable. When a container is used, the bone cement can be
used (while enough pressure is applied) to also expand said
container while promoting fixation within bone. When a permeable
container is used, the delivered bone cement may infiltrate though
its walls and promote fixation and/or adhesion to bone interior
(e.g., intedigitation into trabecular bone).
[0215] In an exemplary embodiment of the invention, the container
diameter is optionally about 5 mm, optionally about 8 mm,
optionally about 15 mm, or higher or lower or intermediate value.
In an exemplary embodiment of the invention, for multi-implant
embodiments, a single implant may have the diameter of, for
example, 3 mm, 2 mm, 1 mm or smaller or intermediate values, for
example, being selected to be less than 50% of a cortical bone
thickness.
[0216] In an exemplary embodiment of the invention, a tensile
element has good tensile resistance capabilities. Optionally, said
tensile rod is bendable, for easier insertion and manipulation
within bone, while a plurality of such rods, when situated and
assembled within bone cavity as an implant, decreases
substantially.
[0217] In an exemplary embodiment of the invention, the tensile
elements (rods) are straight. Alternatively, they are curved or
bended in a desired angle and/or a desired location along the rod
(e.g., "banana" shape or "J"-shape).
[0218] In a preferred exemplary embodiment of the invention, all
materials introduced into body are biocompatible. In additional
exemplary embodiment of the invention, the container, and/or the
tensile element fibers, and/or the tensile element matrix, and/or
the bone cement are made of bio-absorbable material, for example
the fibers formed a bio-absorbable polymer. In additional
embodiment of the invention, additional material and/or medicine
may be added to the filling material (for example to bone cement)
and/or tensile element rods. In an exemplary embodiment of the
invention, antibiotic, and/or osteo-conductive material, and or
osteo-inductive material are added to said implant components.
Optionally or alternatively, other materials may be added, for
example, anti-inflammatories and antibiotics.
[0219] In some embodiment of the invention, the procedure(s)
described in the above embodiments is performed under imaging
devices, such as fluoroscopy. Optionally, radio opaque markers are
provided in one or more of tensile elements, container and/or
cement.
[0220] Alternatively and/or additionally, a guided imaging surgery
is performed.
Straight Bone Channel
[0221] Discussed above are some embodiments where a container,
curved bag 14, is inserted through insertion hole 24 from the
middle of shaft 22 of femur 20 and runs through a longitudinal
channel 11 through femoral neck 20.
[0222] In some embodiments, a longitudinal channel is substantially
straight and passes substantially in parallel only to a shaft 22 of
a femur 22 and a straight, optionally rigid, tensile element is
implanted therein. Such a longitudinal channel is optionally made
in a femur using a straight drill entering the femur from the top
of the femur.
[0223] In some embodiments a longitudinal channel 101 is
substantially straight and passes substantially in parallel only to
the axis of femoral neck 20 of a femur 22 and a straight implant
(tensile element) of the present invention is implanted therein
(FIG. 2 K). Such a longitudinal channel is optionally made in a
femur using a straight drill entering the femur from the side of
the femur opposite the head of the femur (e.g., lateral side) 102,
optionally, over a 3.2 mm diameter K-wire. Alternatively, following
insertion of a K-wire, the channel is expanded by, for example,
inflation of a balloon (not seen in the Figure). FIG. 2L
illustrates a curved longitudinal channel 111 (for example having a
"banana" shape) which begins at the lateral side of the proximal
femur shaft 112. Optionally, such a curved channel 111, is created
using a curved tube, for example made of Nitinol, having a burr at
its head which is connected to a rotator shaft (not seen in the
Figure). Optionally, the curved tube is guided, for example by a
flexible K-wire.
Multiple Channels
[0224] In some embodiments, there are at least two longitudinal
channels, optionally crossing for example a first longitudinal
channel passing substantially in parallel to the axis of a femoral
neck 20 of a femur 22 with a straight tensile element of the
present invention is implanted therein (as described above) and a
second longitudinal channel that passes substantially in parallel
to a shaft 22 of femur 22 with a straight tensile element of the
present invention is implanted therein (as described above).
[0225] FIG. 2M illustrates two channels 121, 122, formed in the
proximal femur, into which two implants are introduced (in a manner
as described in the above embodiments). In some embodiments, the
upper channel is straight 121, and the lower one is curved 122.
Such a combination of two implants may contribute to a better
rotational stability of the bone.
[0226] In some embodiments, two channels are formed (e.g., one
along the trochanter axis and one along the femur axis) and the
implant intersects the two channels, for example, by the cement
inserted in the two channels and/or tensile elements inserted
therein, meeting.
Bagless Implant
[0227] Discussed above are embodiments where longitudinal channel
11 is made in medullary cavity 26 and trabecular tissue. Discussed
above are embodiments where cement 16 is at least partially
contained within a container such as a bag 14 components of which
that constitute at least some of the tensile elements of an implant
of the present invention. In some embodiments, an implant is devoid
of a container such as bag 14.
[0228] In some embodiments an implant (comprising a container
and/or other tensile elements) is implanted inside a longitudinal
channel that runs, at least in part, through cortical bone. An
exemplary such embodiment is depicted in axial cross section in
FIG. 6A and in longitudinal cross section in FIG. 6B.
[0229] In FIG. 6A are seen four longitudinal channels 46, each, for
example, 0.5 mm in diameter running substantially parallel to the
axis of a femoral neck 20 through the compact bone tissue
constituting the walls of femoral neck 20. In FIG. 6B is seen a
single longitudinal channel 46 in longitudinal cross section in
which a linear tensile element 48, (e.g., braided aramid filaments
0.2 mm in diameter) of an implant of the present invention is
disposed. Linear tensile element 48 is optionally held in place
with the help of an anchoring plug 50, which includes two outwardly
biased elastic members of stainless steel in a chevron conformation
and optionally plugs the surrounding cavity.
[0230] Forming 104 longitudinal channels 46 is optionally using
straight bone drilling, for example, using a straight narrow drill
head drilling into the femur from the thigh opposite the head of
the femur.
[0231] Inserting tensile element 48, involves, for example, pushing
anchoring plug into a longitudinal channel 46 with, for example a
stiff rod. Optionally, the elasticity and chevron arrangement of
the elastic members of anchoring plug 50 allows plug 50 to be
easily pushed into a longitudinal channel 46 but resists withdrawal
therefrom.
[0232] When an anchoring plug 50 is pushed sufficiently far into a
longitudinal channel 46, cement 16 is injected into longitudinal
channel 46, substantially as described above, a step substantially
equivalent to a step 108 of inflating a container. Once sufficient
cement has been injected to fill the bags, the procedure is
completed substantially as described above. Optionally, a same
needle is used to insert the tensile element and inject cement.
Optionally, the needle includes a bone drilling head and is also
used to drill the channel for the thread
[0233] Pre-tensioning a tensile element 48 such as a tensile
element described in FIGS. 6A and 6B is optionally performed by
pulling on a tensile element until cement 16 has sufficiently
set.
[0234] In embodiments, a tensile element, whether a container such
as a bag or a elongated tensile element such as a fiber or filament
may be radially tamped against the sides of a longitudinal channel
with the help of a ram or inflatable element.
Water Jet Drilling
[0235] In an exemplary embodiment of the invention, drilling and/or
reaming and/or cutting of bone tissues (trabecular and/or cortical)
are performed by water-jet technique. Using water-jet techniques
for bone surgeries is described, for example, in Schwieger et al
(2004), "Abrasive Water Jet Cutting as a New Procedure for Cutting
Trabecular Bone--In Vitro Testing in Comparison with the
Oscillating Saw"; and Honl et al (2003), "The water jet as a new
tool for endoprosthesis revision surgery--An in vitro study on
human bone and bone cement"; the disclosures of which are fully
incorporated herein by reference. The two articles suggest using
water, optionally with abrasive material (preferably
biocompatible), for drilling small holes (similar to jet diameter)
or cutting bones. In an exemplary embodiment of the invention, the
holes created are substantially larger than jet diameter. Optional
holes diameter is about 5 mm, optionally about 10 mm optionally
about 15 mm, or lower or higher or intermediate value. Optional jet
diameter is about 0.05 mm, optionally about 0.1 mm, optionally
about 1 mm, or lower or higher or intermediate value. Optionally,
the ratio of diameters of hole and jet is in the range of
10:1-1000:1, optionally about 100:1.
[0236] In an exemplary embodiment of the invention, at least two
water jet sources are provided. Optionally, the at least two
sources are radially distant one from the other, to support a hole
formation larger than the jet, for example, of order of the
distance between the jets, which is substantially larger that
individual jet stream projected diameter. Optionally, the at least
two jets can be (in a fixed and/or controllable manner) pointed
perpendicularly to/into the bone, or can be slightly tilted
inwardly (towards each other), or alternatively be tilted
outwardly. The coupled jet sources are optionally rotated around a
central axis thus performing needed drilling or reaming.
[0237] FIGS. 8A-8D illustrate three different exemplary drilling
heads which incorporate water jet drilling/cutting techniques.
[0238] FIG. 8A illustrates a cross section of a hollow tubular
drill head 70 having driller body 71, drilling tip 72, fluid inlet
73 located on its proximal side, fluid basin 74 and a plurality of
openings for fluid-jet ejection. In a preferred exemplary
embodiment of the invention, driller 70 is rotated along its
longitudinal axis and pushed distally into or within bone, such
that drilling tip 72 can drill a hole having a diameter
substantially equal to its largest diameter. An exemplary hole
diameter may be in the range of 0.5-5 mm. Optionally, before,
during and/or after drilling operation performed by rotation of
drilling tip 72, a fluid is pressurized though inlet 73 towards
basin 74, thus a plurality of pressurized fluid jets 76 emerges
laterally through openings 75. In a preferred exemplary embodiment
of the invention, fluid jets 76 have enough impact to cut/engrave
through bone tissues surrounding driller body 71, thus enabling
hole enlargement (with respect to an initial hole made by drill
head 72, and as described in greater detail below) while driller 70
advances within bone. An exemplary enlarged hole diameter may be in
the range of 5-15 mm.
[0239] FIG. 8B illustrates a different exemplary drill head 80
having hollow drilling tip 82, driller body 81 with two concentric
lumens: inner lumen 83 which is in communication with tip 82 and
outer lumen 84 which is in direct communication with openings 85.
As in driller 70, when rotating driller 80, drilling tip 82 can be
used to perform a hole having initial smaller diameter, to be
enlarged by fluid jets 86 that are injected through openings 85 by
pressurizing fluid introduced through outer lumen 84. As
schematically illustrated, the at least two pairs of adjacent
openings 85 may optionally be tilted toward each other. Optionally,
lumen 83 may be used for riding the drill over a guide wire and/or
a small diameter drilling element (not shown), previously
introduced into bone. Optionally or alternatively, lumen 83 may be
used for providing a cutting jet. Optionally or alternatively,
lumen 83 may serve as a channel for other instrumentation(s) (not
shown) to be introduced before, during or after drilling takes
place. Said instrumentation(s) may optionally include, but are not
limited to, collecting or suction devices for removing cut bone
chips, and/or may act as a lumen for suction applied from
outside.
[0240] FIGS. 8C and 8D illustrate two operational modes of a third
exemplary drill head 90. As in driller 80, driller 90 contains
driller body 91 having two concentric lumens: inner lumen 92 which
has similar functionality to inner lumen 83, and outer lumen 93,
which is in direct communication with at least two lateral openings
94. Alternatively, driller 90 has three parallel (non-concentric)
lumens. In an exemplary embodiment of the invention, there are at
least two bendable pipes 95, optionally metal, located in lumen(s)
93. Each pipe 95 optionally includes a distal end 96 which
optionally incorporates mechanical bone cutting capabilities, and
at least one fluid injection port 97, which is optionally tilted
forward of driller 90 to its axis, when the pipes are extended.
FIG. 8C illustrates driller 90 in a closed mode while FIG. 8D
illustrated driller 90 in an opened mode: in the closed mode pipes
95 are substantially within lumen(s) 93, while in the opened mode
pipes 95 are protruded outwardly. In an exemplary embodiment of the
invention, while driller 90 is rotated, fluid jets 98 are injected
distally in front of driller 90 through ports 97, cutting distally
into bone, and pipes 95 distal ends 96 serve as a lateral cutting
heads for enlarging the diameter of a hole created by jets 98.
Expanding Drill Head
[0241] FIGS. 9A-9B illustrate another exemplary excavation
component which comprises of expandable and/or inflatable
circumferential element that enables selection of different working
diameters.
[0242] FIG. 9A shows a cross section view of exemplary driller 54
having core 55, which its distal end 58 is preferably tipped, and
an inflatable and/or expandable cover 56, which is textured and/or
roughened and/or covered with abrasive material as schematically
illustrated by texture 57. Texture 57 may include but is not
limited to abrasive materials such as diamond powder/granules,
silicone carbide powder, sugars (i.e., lactose), salts and
minerals, and/or any other, preferably biocompatible, abrasive
powders and/or may include small cutting edges, such as bone
knifes.
[0243] FIG. 9A presents driller 54 in a closed mode, whereas FIG.
9B presents driller 54 in an opened and/or partially opened mode.
In an alternative exemplary embodiment of the invention, driller 54
distal end includes only an inflatable and/or expandable
element.
[0244] In an exemplary embodiment of the invention, when in closed
mode, driller 54 may act as mechanical driller able to perform
holes in nominal sizes (usually, though not limited to, a diameter
within the range of 0.5-5 mm). When in opened mode, i.e., when
driller 54 is expanded to a preferred diameter (usually, though not
limited to, a diameter within the range of 5-15 mm), driller 54 is
manipulated within bone by peeling techniques such as by rotation
and/or inward-outward maneuvering of the drill, while its textured
surface will be pressed against the hole inner diameter, in order
to promote its widening.
[0245] In an exemplary embodiment of the invention, cover 56 is a
balloon inflated using a fluid lumen (not shown) optionally
communicating between an outside fluid pressure source and an
opening inside of the balloon. In an alternative embodiment, cover
56 comprises a plurality of strips, which bulge out when their ends
are moved closer together, for example, by one end of the strips
being connected to core 55 and the other end to a telescoped
overtube (not shown), whose axial position relative to core 55 is
controllable.
Exemplary Process and Tool Set for Rod-Based Implant
[0246] As noted above, in an exemplary embodiment of the invention,
at least some of the tensile properties of the implant are provided
by a plurality of rods. Following is a description of a method and
tool set for such an implant, in which the drilling is
substantially in a straight line. It should be noted that the
various features, tools and/or property values described herein are
also applicable to other embodiments described herein and vice
versa.
Overview
[0247] FIG. 10A is a flowchart of a method 1000 of composite bone
implant construction and implantation, in accordance with an
exemplary embodiment of the invention. FIG. 10B is a
cross-sectional view of a composite implant 1050 in a femur 1052,
in accordance with an exemplary embodiment of the invention. FIGS.
11-19 illustrate components of a bone implant kit usable for the
method of FIG. 10A, in accordance with an exemplary embodiment of
the invention.
[0248] FIGS. 10C-10I illustrate snapshots of points along an
exemplary process shown in FIG. 10A.
[0249] In an exemplary embodiment of the invention, for the
treatment of proximal femoral fractures, a channel having a
diameter of, for example, 4 mm, or 5 mm, or 6 mm, or 8 mm, or 10
mm, or 12 mm is made, from the lateral side of the proximal femur
shaft, through the femoral neck, up to the femoral head. In an
exemplary embodiment of the invention, an insertion passage is
created in bone, for example a K-wire (having a diameter of, for
instance, 3.2 mm) is introduced. Over the K-wire, an insertion tube
is optionally introduced (followed by the removal of the K-wire).
Optionally, the tube is inserted in a different manner than over a
K-wire. Then, a bag container is introduced and positioned in said
tube and the tube is retrieved.
[0250] A balloon device is then optionally inserted into the
container and inflated, in order to expand the channel (and the
container) within the bone.
[0251] In an exemplary embodiment of the invention, the channel is
expanded using a special K-wire. For example, the K-wire can
include a side extending element that when extended serves to cut
or otherwise break down trabecular bone and/or cortical bone, when
the k-wire is rotated and/or moved axially. Optionally or
alternatively, the K-wire has an expandable tip or an eccentric
tip, for example, as described in PCT publication WO2005/032326,
the disclosure of which is incorporated herein by reference. In
some embodiments, the side extending element is made rigid enough
to cut trabecular bone but bends when contacting cortical bone,
possibly reducing damage to cortical bone.
[0252] Following this optional expansion, the balloon device is
deflated and retrieved, and elongated tensile elements, for example
rods of composite material such as carbon fibers embedded in
polymer matrix, are introduced into the bag container. After a
satisfactory filling of the bag with said rods, filling material
such as bone cement is injected into the bag to fill the gaps
between and surrounding the rods.
[0253] Alternatively, following creating a passage, a balloon
device is introduced into the tube/bone passage prior to bag
container insertion. The tube is removed and the balloon is
inflated, deflated and retrieved, followed by introduction of a bag
container. Then, elongated tensile elements are introduced and
filling material is injected as described above.
[0254] In an alternative exemplary embodiment of the invention,
following removal of the K-wire, a balloon, optionally a balloon
that has a mesh embedded in it for using high pressure for example
100 Bar, covered by a bag container, is inserted into the insertion
tube. Said tube is retrieved, and balloon is expanded. Then,
elongated tensile elements are introduced and filling material is
injected as described above. Alternatively, the bag is inserted
after the balloon is removed.
[0255] Referring specifically to FIG. 10B, when the implant
construction process is completed, implant 1050 is optionally as
follows. A bag 1060 encloses a plurality of rods 1062 and cement
1064 between the rods. An optional elongate rod 1068 reaches along
the entire length of bag 1060, from an aperture 1058 formed in a
cortex 1056 of hip 1052 to a distal end 1074 of bag 1060.
Optionally, end 1074 is reinforced using a metal seal 1070 that
includes a hollow 1076 for receiving a rod and an optional outer
band 1072 for locking seal 1070 to bag 1060. Implant 1050 is shown
generally parallel and along an axis of a trochanter 1054.
Optionally, implant 1050 leans on the cortex of trochanter 1054 at
a point 1078. Optionally, implant 150 rests on cortex at aperture
1058 and point 1078.
[0256] Optionally, bag 1060 includes apertures along its length so
that some cement can leak and form one or more inter-digitations
1084 (only a few shown) to enhance engagement of trabecular bone.
Optionally or alternatively, bag 1060 includes additional apertures
adapted to support greater cement leakage, for example at a
proximal end (forming anchoring section 1080) and/or at a distal
end (forming anchoring section 1082).
Exemplary Tool Set
[0257] FIGS. 11-19 show an exemplary tool set, with matching
handles and wherein all the tools fit through a cannula.
Alternative designs are described after. In addition, it should be
noted that some or all of the tools may be replaced by other tools
and still be used to carry out methods in accordance with an
exemplary embodiment of the invention.
[0258] In an exemplary embodiment of the invention, the tools are
provided as a kit, optionally in a sterile package, optionally with
instructions. The implant components (e.g., bag, cement, rods) may
be provided in a same kit or provided separately. Optionally, the
tools are sterilizable, however, hardening of bone cement may
prevent reuse of at least some of the components.
[0259] In an exemplary embodiment of the invention, the tools are
rigid, for example, formed of stainless steel. Optionally, at least
some of the tools are flexible and optionally provided via a
flexible cannula or endoscope. For example, the drill, cannula, bag
holder, stylet, bag cutter, element carrier and/or cement cannula
may be flexible. Some or all of these tools may be formed of
non-metals, for example, plastic, PEEK, PEKK and/or Composite
materials.
Bone Cannula
[0260] FIG. 11 illustrates a bone access cannula 1100, optionally
used for accessing the bone to be treated, in accordance with an
exemplary embodiment of the invention. Cannula 1100 includes a
shaft 1104 mounted on an optional handle 1102. Optionally, one or
more engagement elements 1114 are provided for interlocking with
other components of the tool set.
[0261] At a distal end 1106 of shaft 1104, a bone cutter 1108, for
example, a serrated edge, adapted for digging into cortical bone is
optionally provided. A straight guide section 1110 is provided
proximal thereto and optionally sits across cortical bone, in use.
A widening cone 1112, or other widening, optionally serves to limit
advancement of top 1106 into bone.
[0262] In an exemplary embodiment of the invention (for hip), the
cannula has a diameter of 6.9 mm diameter and length of 160 mm,
optionally formed of stainless steel working sleeve. The tapered
portion is optionally of a diameter of 4.8 mm and the inner
diameter is optionally approximately 4.2 mm. The handle is
optionally polycarbonate handle.
[0263] It should be noted that smaller sizes may be used in other
bones, and depending on various design variations, for example, as
described below.
Bone Drill
[0264] FIGS. 12A-12E illustrate a bone drill 1200, optionally used
for piercing through soft tissue, drilling though cortical bone,
drilling through trabecular bone and/or widening a pathway in
trabecular bone or/and cortical bone, in accordance with an
exemplary embodiment of the invention. FIGS. 12A and 12B show
different side views of drill 1200.
[0265] Drill 1200 has a shaft 1202 optionally sized to fit in
cannula 1100. A distal end 1204 optionally includes a bone cutting
tip 1206 adapted for drilling into cortical bone, and also usable
for trabecular bone. An optional side extending cutter 1208 is also
shown which is selectively extendible to widen a trabecular or/and
cortical bone channel and when retracted, does not affect the drill
diameter.
[0266] A plurality of markings 1210 is optionally provided. The
markings are optionally radio-opaque. Optionally, the markings are
outside the body and used to indicate the relative position of
distal tip 1204 relative to the distal tip of cannula 1100.
[0267] A recess 1214 is optionally provided for attachment of a
handle and/or a motor (e.g., if a hand-held drilling motor and
handle are provided with a bone treatment kit).
[0268] A proximal end 1212 is optionally provided for controlling
the extension of cutting element 1208, by rotation of a knob 1220.
Other mechanisms may be used as well.
[0269] FIG. 12C is a cross-sectional view of drill 1200, and FIG.
12E a detail of proximal end 1212, showing a threading 1222, which
engages knob 1220. Knob 1220 is coupled to a shaft 1218 which lies
in a lumen 1216.
[0270] Referring also to FIG. 12D, a detail of distal end 1204, a
curved knife element 1224 of cutting element 1208 exits through an
aperture 1230 and is engaged by shaft 1218 using a rotating joint
1226. A space 1228 is optionally designed to receive element 1224
when retracted. In this embodiment, element 1224 optionally does
not change shape during extension/retraction. In an exemplary
embodiment of the invention, element 1224 extends sideways after
being pushed along a rail-like mechanism extending to outside the
body. In embodiments where element 1224 changes shape, it maintains
its rigid shape after the extrusion through aperture 1230.
[0271] In an exemplary embodiment of the invention, drill 1200 has
a 4.2 mm diameter, and a length of 350 mm. Optionally, drill 1220
is formed of stainless steel. This and/or other tools may be formed
of other materials (optionally flexible), including, for example,
Carbon--PEEK, plastics and composite materials or other metals.
Cutting element 1208 optionally extends up to 3 mm away from the
surface of shaft 1202, thereby providing a total drilling diameter
of up to 10 mm diameter.
[0272] In an exemplary embodiment of the invention, tip 1206 of
drill 1200 operates when drill 1200 is rotated in either direction.
Alternatively or additionally, extending element 1208 operates when
drill 1200 is rotated in either direction.
[0273] FIG. 13 illustrates the bone drill of FIGS. 12A-12E mounted
in the bone access cannula of FIG. 11, in accordance with an
exemplary embodiment of the invention. In particular, side cutting
element 1208 is retracted, so dill 1220 fits through cannula
1100.
Stylet
[0274] FIG. 14 illustrates a stylet 1400, optionally used to
maintain a shape of a cement injection cannula and/or of a mesh
bag, in accordance with an exemplary embodiment of the
invention.
[0275] Stylet 1400 has a shaft 1402, an optional knob 1406 for
manipulation thereof and a rounded tip 1404. Optionally, one or
more steps 1408 serve as radio-opaque markers. Other marker types
may be used.
[0276] In an exemplary embodiment of the invention, the stylet is
2.2 mm in diameter and in length of between 145-195 mm. Optionally,
a plurality of sizes are provided, to match different implant
lengths. Optionally, the sizes are in 10 mm increments. A plurality
of sizes may also be provided for drill 1200. Optionally or
alternatively, movable stops (not shown) are provided on the shafts
of one or both of stylet 1400 and bone drill 1200, to prevent over
insertion into the body. Optionally, the desired depth of
penetration is determined by inspecting x-ray images of the treated
bone, before and/or during treatment.
Cement Delivery
[0277] FIG. 15 illustrates a cement delivery cannula 1500,
optionally used for delivering cement into the implant, with stylet
1400 mounted therein, in accordance with an exemplary embodiment of
the invention. In an exemplary embodiment of the invention, cannula
1500 includes a shaft 1502, a cement injection port 1504, adapted
for attachment to a cement/pressure source and an optional lock
1506 for locking to cannula 1100. Optionally, the cement pressure
source (not shown) is a syringe and/or a hydraulic cement pump.
[0278] In some embodiments, cement is provided directly through
cannula 1100 without an additional cement delivery cannula. Where
provided, cannula 1500 may be short, reaching only to a proximal
side of the implant, for example, reaching to a forward tip 1508.
In other embodiments, cannula 1500 reaches to a distal end of the
bag, for example, to a tip 1510.
[0279] In an exemplary embodiment of the invention, cannula shaft
1502 has a diameter of between 3.4 mm and 2.62 mm. Optionally, the
variation in diameter (within a device) is used for one or both of
blocking cement backflow (see 1508 below) and/or providing
pushability to cement cannula 1500. Optionally, the length of the
cannula varies according to the usage. Optionally, the diameter
narrows along the cannula, starting, for example, at 3.4 mm and
narrowing to 2.2 mm at point 1508, which is optionally designed to
match the narrowing in cannula 1100. Optionally, the use of a wider
diameter section allows resistance to cement injection to be
reduced.
[0280] In an exemplary embodiment of the invention, stylet 1400
inserted inside cannula 1500 before the injection to keep cannula
1500 straight.
Bag Holder
[0281] FIGS. 16A-16C illustrates a bag holder 1600, used for
holding a mesh bag and providing access thereto during the
implantation procedure, in accordance with an exemplary embodiment
of the invention.
[0282] In an exemplary embodiment of the invention, the mouth of
the bag is held between two tubes, optionally of stainless steel.
Axially separating the tubes releases the bag. Alternative holding
and releasing methods are described below.
[0283] FIG. 16A is a side view and FIG. 16B is a cross-sectional
view of holder 1600. FIG. 16C is a detail of the bag holding
mechanism.
[0284] Holder 1600 has a handle 1604 coupled to a shaft 1602 that
acts as an outer tube. A second handle 1606, optionally lockable to
handle 1604 is coupled to an inner tube 1608. the bag (1614) is
held between tubes 1602 and 1608. A sleeve 1610, which is
optionally sized to enter into the bone or at least cross the
cortex, optionally serves as a guide into the bag and optionally
assists in aiming rods 1062 as they are inserted.
[0285] Referring specifically to FIG. 16C, bag 1614 is pinched at a
point 1616 between distal ends of tubes 1608 and 1602, where there
is a narrowing (e.g., a step narrowing as shown, or a gradual
narrowing) of tube 1602. A neck of bag 1614 is optionally located
in a space 1612 between the tubes
[0286] In an exemplary embodiment of the invention, holder 1600 has
an outer diameter of 4.2 mm, so it fits inside cannula 1100, in an
extra-bone portion thereof. Outside diameter of 4.2 mm, length of
180 mm.
[0287] FIG. 17 illustrates stylet 1400, mounted in cement delivery
cannula 1500, mounted in bag holder 1600, all mounted in bone
access cannula 1100, in accordance with an exemplary embodiment of
the invention. Optionally, stylet 1400 is used to hold the bag
straight during insertion. In other embodiments, a rod 1062 is used
as a stylet for inserting the bag.
Rod Carrier
[0288] FIGS. 18A-18B illustrate a rod carrier 1800, used for
inserting and releasing rods 1062 into bag 1614, in accordance with
an exemplary embodiment of the invention. FIG. 18A is a side view
and FIG. 18B is a cross-sectional view.
[0289] In an exemplary embodiment of the invention, rod 1062 is
held by a tight fit or friction inside a lumen of a shaft 1802 of
carrier 1800, resting against a narrowing in the lumen (which may
have a gradually narrowing inner cross-section, when advancing from
distal end proximally) and/or against a tip 1814 of a piston 1808.
A short section 1810 of shaft 1802 serves as a holder for the tip
of rod 1062. To release, piston 1808 is advanced and/or tube 1802
retracted while maintaining piston 1808 in place, such that the
proximal end of rod 1062 is released.
[0290] In an exemplary embodiment of the invention, tube 1802 is
coupled to a handle 1804 and piston 1808 is coupled to a
push-button or other actuator 1806, which is optionally coupled by
a spring 1812 to handle 1804.
[0291] Optionally, the diameter of shaft 1802 is 3.4 mm and the
length is 280 mm. Optionally, a forward tip 1816 of carrier 1800
does not enter into the bone and/or does not enter past the cortex.
Alternative designs are shown below.
[0292] FIG. 19 illustrates rod carrier 1800, mounted in bag holder
1600, all mounted in the bone access cannula 1100, in accordance
with an exemplary embodiment of the invention.
[0293] Described below, after the process, in greater detail are
bag 1614 and rods 1062.
Exemplary Implant Construction Process
[0294] Referring back to FIG. 10A, the process of constructing an
implant in situ in accordance with exemplary embodiments of the
invention and using the tool set just described, is now
detailed.
Identify a Need (1002)
[0295] In an exemplary embodiment of the invention, the need is
identified based on several factors including but not limited to:
bone illness and porosity, patient age and medical history, the
current state of the opposite/twin bone.
[0296] In an exemplary embodiment of the invention, the need
answered is a cracked or weakened trochanter. In some cases, this
is identified by x-ray, by ultrasound and/or by fractures in other
bones. Optionally or alternatively, identification is by a general
measure, such as osteoporosis and/or age. In an exemplary
embodiment of the invention, when a patient exhibits a fracture or
other bone damage in one limb, this is taken as an indication that
a treatment should be carried out for the mirroring limb. A same or
different treatment may be provided to the obviously damaged
limb.
[0297] In an exemplary embodiment of the invention, due to the
reduced invasiveness, a reduced amount of painkillers and/or
anesthesia may be used, and/or a lower level of anesthesia, for
example a local nerve block. Optionally, no unconsciousness is
required.
[0298] In an exemplary embodiment of the invention, a candidate
patient for a preventive surgical treatment as described herein is
an aged person (over 60 years old) with moderate osteoporosis
specifically identified in his/her femoral bones, and with a first
fractured and/or cracked femur and a second femur optionally not
fractured or cracked. In such an exemplary case, both femurs or at
least one of the two femurs may be treated with the method
described herein.
[0299] Optionally, a desired shape/type of implant(s), size of
implant (length and/or diameter) and/or mechanical priorities are
determined, for example, based on the image and/or mechanical
considerations. Optionally, this leads to selecting a suitable
implant kit and/or relative amounts of rods and cement, size of bag
and/or lengths of components in the kit. Optionally, if stops are
provided on the tools, the stops are set to a desired implant
length.
[0300] Optionally, a table, software and/or stand alone calculator
are provided to match up the various needs with the implant
properties and/or components.
Cutting the Skin (1004)
[0301] The skin is cut, optionally using a surgical opening, for
example, an incision of 5-40 mm long. Optionally, the opening is a
puncture, for example with an initial diameter of 2-10 mm and
access to the bone is minimally invasive.
Tunnel to Bone (1006)
[0302] In an exemplary embodiment of the invention, a path to the
bone is formed by advancing drill 1200. Optionally or
alternatively, the path is formed by a trocar and/or stylet.
Optionally or alternatively, there is no need to form a path, for
example, if a surgical incision is used or if bone is near the skin
surface. Cannula 110 is optionally mounted on drill 1200 and its
handle used for assistance. Optionally, cannula 1100 is lockable to
drill 1200 using a lock (not shown), optionally activated by axial
advance of cannula 110 over drill 1220 until it snap locks.
Optionally or alternatively, cannula 1100 engages drill 1200 by
threading thereto at proximal ends thereof.
Open Cortex (1008)
[0303] Drill 1200 is inserted and rotated into cortex 1056, to form
aperture 1058 therein. Optionally, aperture 1058 is between 2 and 5
mm in diameter, depending, for example, on the bone and/or illness
characteristics, rod dimensions and/or bag thickness.
[0304] Such drilling may be, for example, manual, or using a motor
to rotate and/or vibrate drill 1200.
Engage Cortex (1010)
[0305] Cannula 1100 is advanced so that cortex cutter 1108 cuts
into the cortex, widening the hole formed by drill 1200 and, once
tip 1106 of cannula 1100 is advanced, engaging cannula 110 to the
bone using friction and setting a gateway for accessing the bone.
Optionally, cannula 110 is used to suck debris out of the wound
and/or provide washing fluid therein. Optionally, drill 1200 is
removed for suction. Alternatively or additionally, drill 1200
includes a suction lumen therein. Such a lumen may also be used to
provide fluid and/or suction while drilling.
[0306] In some embodiments, the cortex is engaged after drilling
using drill 1200 is completed, or at least after a most distal
point in the bone is reached.
[0307] In some embodiments, cannula 1100 does not enter to cortex
and the cortex is not engages or is engaged from its outside. This
provides for a smaller aperture 1058. Alternative stabilization
means may be used, for example, as described below.
Create Channel (1012)
[0308] Drill 1200 is advanced towards the end of trochanter 1054,
forming a channel in the bone. Optionally, the channel reaches, but
does not contact the cortical bone at the end of the trochanter.
Optionally, a distance between 3-7 mm is maintained. In an
exemplary embodiment of the invention, the distance is selected to
reduce damage to blood vessels and/or to reduce chance of damage to
the femoral head. Different distances may apply to other bones,
anatomies and/or patient conditions.
[0309] In some embodiments, a different drilling tool is used for
drilling through trabecular bone.
[0310] Once drilling is completed, the channel may be washed and/or
cleaned up, for example, using fluid and/or suction via cannula
1100.
[0311] FIG. 10C shows drill 1200 inside a channel 1090, formed as
described herein.
Enlarge Cavity (1014)
[0312] The channel is optionally enlarged to fit the desired size
of implant, optionally an exact fit. Alternatively, an undersized
or oversized cavity may be formed, the lack of fitting in one or
more dimensions. In an exemplary embodiment of the invention, the
channel is enlarged by cutting using cutting element 1208, while
rotating and/or retracting of drill 1200. this process may be
manual or motorized, with a motor optionally coordinating the axial
and rotational movements to ensure that element 1208 contacts bone
on all sides of the channel. Other tools as described above can be
used as well.
[0313] In an alternative embodiment, the channel is enlarged into a
cavity by crushing, for example, by inserting a crushing balloon or
by inserting bag 1614 at a small diameter and then expanding the
bag by injection of cement and/or insertion of rods.
[0314] In an exemplary embodiment of the invention, the enlarged
cavity is of a diameter of between 150% and 400% of that of the
(initial) channel, for example, between 200% and 350%. In some
cases, some cortical bone is removed as well. In other cases the
canal may curve to avoid cortical bone or may be narrow at a
location where cortical bone protrudes into the canal.
[0315] FIG. 10D shows drill 1200 with extending element 1208 having
formed an enlarged cavity 1092.
Verify Cavity (1016) (Optional)
[0316] Optionally, the existence and/or geometry of the cavity is
verified before the implantation process continues. Optionally, the
verification is from outside the body, for example, using
ultrasonic imaging or x-ray imaging. Alternatively or additionally,
the verification is by imaging via cannula 110, for example
inserting an optical or ultrasonic imager into the cavity.
Alternatively or additionally, the verification is mechanical, for
example, expanding a balloon or a winged element inside the cavity
to a desired diameter and determining that the expanded element is
free to move. Optionally or alternatively to verifying the
diameter, the length of the cavity is determined, for example,
based on positions of radio-opaque markers of drill 1200, relative
to cannula 1100. Such markers are optionally located so they remain
outside the bone and/or outside soft tissue. Optionally, this
length is used to set the lengths of tools for the rest of the
procedure and/or select the bag.
Insert Container/Bag (1018)
[0317] Drill 1200 is optionally removed from cannula 110 and bag
holder 1600 having a bag mounted thereon is inserted (e.g., for
bag-based implants).
[0318] Optionally, stylet 1400 is used to guide the insertion of
the bag and ensure the bag is inserted straight and not folded
and/or twisted. In some embodiments, a rod 1062 is used as the
stylet, as described below, for example.
[0319] In some embodiments of the invention, bag 1614 is provided
pre-mounted on holder 1600. In other embodiments, the bag is
mounted when used. Optionally, the bag is placed into tube 1602 and
then tube 1608 is advanced until it pinches bag 1614 between the
tubes. Optionally, the bag has length markings thereon which can be
matched to the length shown for the cavity. In some embodiments,
the bag is cut to size, for example using a cutter (e.g., an anvil
cutter), not shown, provided with the kit.
[0320] In some embodiments, the bag is inflated, for example, by
injection of some cement and/or by inserting a balloon, inflating
the balloon and then deflating and removing the balloon.
[0321] If bag 1614 is not advanced all the way to the end of the
cavity, the spacing between may be filled with cement, for example,
as described below.
[0322] FIG. 10E shows bag 1614 placed in cavity 1092. An
exaggerated space is shown between the distal end of bag 1614 and
the edge of the cavity. Optionally, this distance is a few mm
(e.g., 3, 4, 5, 6) and is later filed with cement that seeks form
the bag. In other cases, such a space does not exist and/or is
considerably smaller (e.g. 1-2 mm).
Rod Insertion (1020)
[0323] Stylet 1400 (and optionally cannula 1500) are removed and a
first rod 1062 is inserted, mounted on rod carrier 1800. When
carrier 1800 (and/or rod 1062) is inserted all the way, piston 1808
is advanced while allowing shaft 1802 to recoil and rod 1062 is
released into the bag.
[0324] In an exemplary embodiment of the invention, a plurality of
rods, for example, 4-20, optionally 4-10 or about 7 are inserted,
one after another. As shown below, the rods are optionally designed
to slide past each other. Optionally, bag 1614 is not tightly
filled with rods. Rather, the rods only fill 40%-60% or 70% of the
volume of bag 1614.
[0325] Optionally, the rods are cut to size before insertion, or a
plurality of rod sets of different sizes are provided. Cutting
optionally uses a cutter (not shown) optionally provided with the
kit.
[0326] In an exemplary embodiment of the invention, the rods are
cooled prior to use. Optionally a cooling element (not shown), such
as a paltier element and/or a cooling pack receptacle, being
provide din the rod pusher. Optionally, such cooling offsets, at
least in part, heat generated by cement setting.
[0327] FIG. 10F shows a rod 1062 already inserted into bag 1614 and
a second rod 1062 being inserted.
Cement Injection (1022)
[0328] Cannula 1500 is inserted, optionally using stylet 1400 to
assist in the cannula reaching to the distal end of the implant. In
other embodiments, the cannula reaches only to the proximal end of
the implant. Optionally, a relatively tight seal is formed between
cannula 1500 and cannula 110, to prevent cement which is injected
under pressure from exiting the bone and possibly preventing proper
implantation and/or damaging tissue.
[0329] In an exemplary embodiment of the invention, the cement
injection fills in between the rods and also optionally leaks out
of bag 1614. Optionally, leakage at a distal and/or proximal end
and/or at other designated locations along the bag (e.g., adjacent
resting 1078), are selected to provide anchoring sections
optionally at least 10% of the implant length in length and/or
optionally at least 50% of the implant diameter in radial
direction. For the bag, formed of cement and/or ensure cement
contact with cortical bone. Optionally, the bag includes one or
more openings for such specific leakage. Optionally, one or more
filaments are provided at such openings to be carried along with
the cement and provide some support for the cement, optionally as a
tensile element.
[0330] Optionally or alternatively, additional leakage at specific
points or all along the bag, is used to form inter-digitations with
trabecular bone. Various possibilities are described below.
[0331] In some embodiments of the invention, cements of multiple
viscosities are injected, for example, low viscosity cement, to
better leak form the bag and/or fill in between the rods and then
high viscosity cement, to ensure closure of aperture 1058.
[0332] In some embodiments, no cement is injected. Optionally, rods
are inserted into the bag until there is no room for more.
Alternatively or additionally, an adhesive is provided, which
optionally adheres the rods together.
[0333] FIG. 10G shows the insertion of a stylet 1400 to guide
cement delivery cannula 1500 into the implant.
[0334] FIG. 10H shows cement cannula 1500 filling the bag with
cement (stylet 1400 is removed so a cement source can be
attached).
Last Rod Insertion (1024) (Optional)
[0335] Optionally, after cement injection is completed, last rod
1068 is inserted. In an exemplary embodiment of the invention, this
last rod engages aperture 1058. Optionally, rod 1068 has a flat or
rounded proximal end. Optionally or alternatively, to inserting a
rod, a cap is inserted. Such a cap optionally includes a proximal
section of dimensions of aperture 1058 or greater (to act as a
cap), for example, a cone shaped element. Optionally, the cap
comprises a rod of a length shorter (e.g., 70%, 50%, 30% or greater
or intermediate values) than other rods and serves to lock the
implant to the cortical bone (e.g., at the proximal side thereof).
Optionally, an expanding element is inserted into the implant to
perform such locking Optionally, the diameter of the final rod is
greater (e.g., by 50%, 80%, 100%, 150%, 200% or greater or
intermediate values) than of the other rods and/or is formed of a
more rigid material.
[0336] In an exemplary embodiment of the invention, rod 1068
increases the pressure inside the implant.
[0337] Optionally, backflow of cement is prevented by providing the
rod and/or rod pusher with a closer fit to cannula 1100 and/or
providing the rod and/or rod pusher with a o-ring type seal, which
optionally moves back as rod is advanced.
[0338] Optionally, receptacle 1076 (of bag distal end) is sized
small enough so only a forward tip of rod 1068, which is optionally
made smaller than those of rods 1062, can fit therein. Optionally
or alternatively, the last rod is positioned under x-ray
control.
[0339] In an exemplary embodiment of the invention, the last rod is
hollow and is used for injection of some or all of the cement into
the implant. The last rod may include a forward aperture and/or one
or more side apertures along its length.
[0340] FIG. 10I shows the insertion of a last rod 1068 into the
implant.
Residual Container Removal (1026)
[0341] Rod carrier 1800 is optionally maintained in place until the
cement sufficiently hardens. Thereafter, the portions of bag 1614
that are outside of the bone are optionally removed. In an
exemplary embodiment of the invention, the portions are removed by
cutting the bag, for example using a cutter as described below.
Optionally, tube 1608 has a serrated or other cutting edge and when
rotated, cuts bag 1614 at location 1616. Alternative bag release
methods are described below.
End Procedure (1028)
[0342] The procedure is completed, for example, by suturing the
entry hole into the body. Optionally, the leg and/or other limb can
be used immediately or after a short rest, for example, to allow
the cement to set.
Anchoring of Tools
[0343] In an exemplary embodiment of the invention, the tools are
anchored to the bone by cannula 110 rigidly engaging the bone
(e.g., using friction). This can also provide a seal between the
bone and other tissue.
[0344] Optionally or alternatively, fixation is provided by other
means. In one embodiment of the invention, a framework, for example
a guiding tube, or cannula 1100 (or other guiding framework, is
attached to the body using external straps or other means, such as
a framework, that are mounted on the body. Optionally or
alternatively, the guide is attached to the body using fixation
screws. Optionally or alternatively, the guide is attached to a
bed/chair on which the body is supported.
[0345] A potential problem when not using cannula 1100 as described
herein is that the bag may not lie/remain along the channel. In an
exemplary embodiment of the invention, the bag includes at least
one elastic fiber that urges the bag to remain in a straight (or
other desired) configuration, which matches the channel.
Optionally, the ends of the rods are machined/formed so their
leading edge does not catch on the mesh of the bag.
[0346] A potential advantage of not using cannula 1100 to engage
the bone is that a reduction in aperture diameter can be
achieved.
Position and Depth Determination
[0347] In some embodiments it is desirable to know the length of
implant and/or distance from forward cortical bone. In an exemplary
embodiment of the invention, radio-opaque markers are provided, for
example, as described above with respect to FIG. 12. Optionally or
alternatively, optical marks and an optical encoder reader are
provided to determine the relative position of various tools.
[0348] In an exemplary embodiment of the invention, an ultrasonic
sensor is provided at the tip of a tube, for example, stylet 1400
and used to determine a forward distance to cortical bone.
Optionally, a user audible/visual signal is generated when the
distance is correct. Optionally or alternatively, a signal is
generated when the distance is too close or too far.
[0349] Optionally or alternatively, a side looking sensor is
provided and used to indicate if the implant or channel/void lie
close enough to cortical bone on the side.
[0350] In an exemplary embodiment of the invention, side distance
is sensed by extending the side cutting tool until it touches
cortical bone and noting the distance extended (e.g., on the
extending manipulator or using radio-opaque markers). Optionally or
alternatively, a forward extending tip (e.g., a wire) is used to
sense distance to forward cortical bone.
[0351] Optionally, when the implantation process is complete
(possibly before cutting the residuals), the implant is pulled back
against the proximal cortical bone.
[0352] In an exemplary embodiment of the invention, drill 1200
(and/or other tools) is positioned (e.g., its position determined
and optionally changed manually) using a position sensor as known
in the art. For example, for rigid tools, a position sensor may be
attached to the handle of the tool, with the body including a
reference. Optionally, two position sensors, one on cannula 1100
and one of any tool used, indicate the relative position.
Optionally, the body reference is calibrated to a previously
acquired image, so that the position of the various tools can be
shown overlaid on the previously acquired image. Optionally, the
image is a 3D image and/or shown in 3D.
[0353] For non-rigid tools and/or some position sensor types, a
probe and/or emitter may be mounted on the tool itself, for
example, at a distal end of drill 1000.
[0354] Optionally or alternatively, the implant and/or tools are
positioned using other means, such as x-ray (optionally two
perpendicular imagers), MRI, CT, or other means known in the
art.
Alternative Void Formers
[0355] FIGS. 20A and 20B an alternative side drill extension, in
accordance with an exemplary embodiment of the invention. Rather
than a sharp cutting element (optionally trans-axially aligned), a
wire 2006 is extended though an aperture 2004. FIG. 20A shows wire
2006 retracted and FIG. 20B shows wire 2006 extended. A potential
advantage of a wire is that it may be easier to deform during
delivery and/or provided at various extensions. Optionally,
rotation at a relatively higher speed is used with wire-based
cutting.
[0356] In an exemplary embodiment of the invention, manufacturing
comprises forming a lumen in the shaft of drill 1200 and mounting a
new tip (an exemplary seam 2008 shown) thereon, including the
forward cutting edge and channels for guiding wire 2006.
[0357] FIG. 20C-20E illustrate another alternative side drill
extension, in accordance with an exemplary embodiment of the
invention. FIG. 20C shows the extension retracted. FIG. 20D shows
the extension extended and FIG. 20E is a side-cross-sectional
view.
[0358] In the embodiment of FIG. 20C-20E, an extension cutting
element 2012 has a cutting edge 2014. Element 2012 is optionally
super-elastic, so that when released (by its extension 2020
advanced distally, it curves out of an aperture 2010. Optionally, a
guide such as in FIG. 12D is provided. Optionally or alternatively,
the guide serves to actively shape the extension as it is
extended.
[0359] In the embodiment shown, a space 2018 is provided inside the
tip of drill 1200. Optionally, a shield 2016 prevent entry of bone
material into volume 2018 and/or such material collects in space
2018, rather than interfere with movement of the extension.
Optionally, shield 2016 is elastically disposed to seal against
extension 2012.
[0360] Optionally, the embodiment of FIG. 12 uses a stainless steel
cutting extension which is not markedly deformable and which may be
easier to vibrationally move in and out, for example, to assist in
drilling. Such motion may be provided with other embodiments
described herein.
[0361] While a single extension is shown, the extension may be
formed of several elements and/or may be forked. Optionally or
alternatively, two or more extensions are extended from different
sides of the drill tip.
[0362] Optionally, the angle of the extension is about
perpendicular to the drill shaft. In other embodiments, the angle
is greater or lesser, for example, being between 30-50 degrees away
from the perpendicular.
[0363] In some embodiments, rather than a cutting edge, a
thickening is provided at the tip of the extension. Optionally,
this tip assists in cutting parallel to the drill axis. Optionally
or alternatively, this tip smoothes the inner wall of the cavity.
Optionally or alternatively, this tip serves to cover the exit
aperture when the extension is retracted.
Alternative Rod Pusher
[0364] FIG. 21A-21B illustrate multi-rod carriers, in accordance
with exemplary embodiments of the invention.
[0365] FIG. 21A shows a multi-rod device 2100, including a magazine
2104 which holds a plurality of rods 2300 (See FIG. 23).
[0366] A piston 2108, which is pulled back using optional handle
2110 allows a next rod to enter into a lumen of shaft 2102. When
advanced, piston 2108 pushes the rod into location. An optional
spring 2106 urges rods 2300 towards the lumen.
[0367] In this manner, a user can simply retract and advance piston
2108 for inserting rods and does not need to remove the holder form
cannula 110 for each rod, nor separately mount each rod in the rod
carrier.
[0368] In the embodiment of FIG. 21B, a multi-rod device 2150 uses
a same shaft 2152 for rod insertion, bag holding and/or cement
provision. Optionally, as shown, a bag 2156 is mounted at a
mounting point 2154, for example, using one of the methods
described herein, such as an outer pressure band or adhesive.
Optionally or alternatively, a piston 2158 is hollow and can serve
to inject cement via a lumen 2160 thereof, provided via an optional
connector 2164. Optionally, there are provided a retracting means
to push a rod back into the magazine, for example, a plunger
opposite the magazine (not shown) and/or locking means are provided
to lock the rods in the magazine (for example, a pin in the side of
the magazine (not shown)).
[0369] In a particular implementation, shaft 2152 is formed to
include a bone penetrating tip (e.g., in the form of a needle,
optionally faceted) and the bag is provided through lumen 2160.
Optionally, the bag includes a rigid ring at its neck which engages
a narrowing of lumen 2160. The bag is optionally pre-mounted on a
first one of the inserted rods. Optionally or alternatively, the
last inserted rod is hollow and is used for cement injection.
Optionally or alternatively, a first rod is hollow and used for
injecting cement so as to crush surrounding trabecular bone and/or
inject fluid so as to inflate the bag.
[0370] Optionally or alternatively, a same plunger is used for
moving the rods as for pumping cement into lumen 2160. Optionally
or alternatively, electrical control (e.g., of one or more motors)
is used. Optionally or alternatively, a different switch and/or
switch position is provided for each stage of operation. Optionally
or alternatively, no need to manually manipulate any separate
implant component exists.
[0371] Optionally, when retracted, the ring of the bag breaks
and/or the needle breaks, leaving the implant in bone.
Optional Automation
[0372] In an exemplary embodiment of the invention, the mechanism
of FIG. 21B is automated, for example, using a controller (not
shown) which advances rods until a certain number is inserted or a
resistance felt and then injects cement, to a given amount and/or
until a certain resistance is felt. Optionally, a pressure sensor
(not shown) is provided between a handle 2162 of piston 2158 and a
pushing motor, to sense rod resistance pressure. Resistance to
cement flow and/or volume are optionally sensed by an attachment
(not shown), between the cement source and lumen 2160, for example
mounted on connector 2164.
[0373] Optionally, the controller is electro-mechanical. Optionally
or alternatively, the controller is electrical. Optionally, a user
inputs to the controller the volume of cement and number of rods to
use. Optionally or alternatively, the user indicates an implant
type and the rest is determined automatically.
[0374] Also noted above was the possibility that a motor mechanism
(e.g., motor and gearbox) would serve to rotate and retract drill
1200 in a controlled manner so as to correctly widen the bone
cavity. This can be especially useful if a small side cutting
element and slow rotation are used, as manual control may be
difficult in such cases.
[0375] FIG. 22 illustrates a multi-tool system 2200, in accordance
with an exemplary embodiment of the invention.
[0376] A first part of system 2200 is a controller/actuator section
which may be useful for the embodiment of FIG. 21B as well and/or
for drill control.
[0377] A controller 2202, for example a microcontroller or a
computer uses an optional user input (e.g., keyboard, mouse,
optional display 2208, buttons, knobs) to obtain instructions. A
memory 2206 is optionally used to store instructions, settings,
configuration data and/or machine commands. An actuator 2210
provides power to a selectable mechanism as described below.
Optionally, the actuator comprises a plurality of motors and/or
sensors. A power delivery mechanism 2212, such as a shaft couples
the actuator to a tool connector 2214. In an exemplary embodiment
of the invention, connector 2214 is of a type used in CNC
multi-tool machines. For example, controller 2202 can select to
operate a drilling guide wire tool 2220, and attaches connector
2214 to a base 2222 of the guide wire. Movements in various
required directions, such as axial, rotational and optionally
lateral, are optionally provided. Additional shown tools (not all
of the three need to be provided) are a bag holder 2216 with a base
2218 and a rod carrier 2224 with a base 2226. In alternative
embodiments, all the tools are mounted on the actuator and rotated
or slid into action.
[0378] In an exemplary embodiment of the invention, the system
(optionally excluding the controller portion) is enclosed in a
housing 2228. In use, an initial access to the bone may be provided
manually and the rest of the procedure continues under automatic
control. Optionally, a user can verify each stage in the procedure,
stop the procedure and/or make changes, if desired.
Exemplary Cement
[0379] In an exemplary embodiment of the invention, the cement is
injected in a viscous fluid state. Alternatively or additionally,
the cement is injected in a liquid or semi-liquid state. In an
exemplary embodiment of the invention, the cement viscosity and/or
inclusion of particles therein is selected according to the pore
sizes of bag 1614 and/or a desired degree of cement leakage.
[0380] In an exemplary embodiment of the invention, the cement has
a viscosity which allows the cement to wet all the rods and the bag
inner surface and/or fill the implant with less than 30%, 20%, 10%,
5% or intermediate percentages of void volumes.
[0381] In another embodiment of the invention, the filling material
is a mixture of reinforced material, such as, for example, bone
cement with chopped carbon fibers or bone chips and/or other
fiber-reinforced cement. Optionally, said reinforced material is
introduced in addition to tensile elements. Alternatively, tensile
elements, such as elongated rods, are not used. In an exemplary
embodiment of the invention, a "composite cements" such as
Cortoss.RTM. is used.
[0382] Optionally, a non-setting cement is used, for example a bone
slurry, which fixes after a relatively long period. Optionally, the
bag and rods (if any) provide cohesion to the implant until such
setting.
[0383] In an exemplary embodiment of the invention, a weaker cement
is used, for example, a cement which releases less heat as it sets,
as at least some of the strength of the implant is provided by the
tensile elements.
[0384] In an exemplary embodiment of the invention, the cement used
is the Disc-O-Tech Confidence/Ultra High Viscosity Bone Cement
("Confidence Cement"). The Confidence Cement is a self setting,
high viscosity, radio-opaque acrylic bone cement (PMMA).
[0385] In an exemplary embodiment of the invention, biodegradable
and/or bioabsorbable cements, such as Kriptonyte and calcium
phosphate are used.
Exemplary Rod and Tensile Element Design
[0386] Typical tensile elements comprise elongate objects such as
filaments, monofilaments and multifilaments such as fibers, cables,
threads, wires and strings. In some embodiments, a tensile element
is an aggregate of a plurality of elongate objects such as yarns,
braids, crochets and knits having a certain, limited, degree of
axial extensibility. Typical materials from which tensile elements
of embodiments of the present invention are fashioned include but
are not limited to stainless steel wires, polyamide fibers
(Nylons), aramid fibers (e.g., Kevlar.RTM. from E.I. du Pont de
Nemours and Company and Twaron.RTM. from Teijin Twaron B.V.,
Arnhem, The Netherlands), polyethylene fibers (especially HMW or
UHMW fibers e.g. Dyneema.RTM. from Koninklijke DSM N.V., Heerlen,
The Netherlands) or Spectra.RTM., liquid crystal polymers (e.g.,
celanese acetate, Vectran.RTM.), carbon fibers, and composite
materials such as rods made of carbon fibers in PEEK-OPTIMA.RTM.
polymer matrix (e.g., ENDOLIGN.TM., Invibio Biomaterial Solutions,
UK), Carbon--PEKK (e.g., OXPEKK.TM., Oxford Performance), Carbon
fibers--PMMA and DYNEEMA fibers--PMMA. Typical filaments sizes
range from 10 Dtex to 600 Dtex, optionally 20 Dtex to 440 Dtex,
optionally around 20 to 30 Dtex, such as 25 Dtex.
[0387] In embodiments, at least some or all of the tensile elements
are bioresorbable. In embodiments, at least some or all of the
cement is bioresobable
[0388] In an exemplary embodiment of the invention, the tensile
elements are formed as at least one elongated rod made of a
composite material, such as, for example, elongated carbon or metal
fibers, embedded/"glued" together and/or encapsulated by material
which serves as a matrix (for example, a polymer such as
PEEK-OPTIMA.RTM.).
[0389] In an exemplary embodiment of the invention, a single
composite material rod (tensile element) includes at least 40%,
50%, 60%, 70% or more or intermediate percentages by volume of
longitudinal fibers (for example carbon fibers). In an exemplary
embodiment of the invention, the composite material rod is
manufactured prior to the procedure itself, in order to achieve
good impregnation of all fibers within the polymer matrix.
[0390] In an exemplary embodiment of the invention, the rod is
formed of titanium. Optionally or alternatively, the rod has
tantalum or other radio-opaque material added thereto, for example,
at either end, in a middle and/or in a diffuse manner. This may
assist monitoring of process.
[0391] In an exemplary embodiment of the invention, each tensile
element has good tensile resistance capabilities. Optionally, said
tensile rod(s) is flexible, for easier insertion and manipulation,
while a plurality of such rods, when situated and assembled as an
implant in filling material within bone cavity, is substantially
less flexible.
[0392] In an exemplary embodiment of the invention, flexible
tensile elements have an elastic modulus of between 0-10 Gpa,
optionally 1-5 Gpa and rigid rods have an elastic modulus of
between 10-200 Gpa, optionally 10-50, or 40-120, or more.
[0393] In an exemplary embodiment of the invention, the tensile
elements (rods) are straight, yet, optionally flexible enough for
their manipulation within the bone while inserted. Alternatively,
they are curved or bended in a desired angle and/or a desired
location along the rod (e.g., "banana" shape or "J"-shape).
Optionally, the rods are configured to be curved/bended during
their manufacturing. Alternatively, the straight rods undergo a
treatment, such as thermal treatment, to gain the desired
shape.
[0394] In an exemplary embodiment of the invention, the maximal
diameter of a composite material rod may be, for example, 0.1 mm,
0.5 mm, 1 mm, 1.5 mm, 2 mm, 4 mm, 5 mm or smaller or intermediate
or greater diameters.
[0395] In an exemplary embodiment of the invention, the fibers
within the composite material rod are having a diameter in the
order of micron/s. Optionally, the rod matrix material is a second
bone cement, which may be similar to- or different than the bone
cement that is to be introduced into bone during the surgical
procedure as described above. Optionally, the matrix material is
bindable and/or crosslinkable to the bone cement introduced into
bone during the surgical procedure. In an exemplary embodiment of
the invention, all materials introduced into body are
biocompatible.
[0396] In an exemplary embodiment of the invention, the tensile
elements are smooth. Alternatively, they may be coarse and/or with
protrusions in order to resist axial movements and/or to gain
better adhesion/gluing within the filling material (e.g., bone
cement) and/or between the elements themselves.
[0397] FIG. 23A illustrates a tensile rod 2300, in accordance with
exemplary embodiments of the invention.
[0398] Rod 2300 includes a body 2302, and a distal end 2304, which
is optionally rounded (to better fit between previous rods and not
tear bag 1614) and a proximal end 2306 which is optionally inclined
to support sliding past of ends 2304 of other rods.
[0399] In an exemplary embodiment of the invention, the diameter of
the rod depends on the bone and/or implant sizes. Optionally, the
rods are between 20 and 400 mm long. Optionally, for a particular
usage, such as trochanter repair, the rods are between 50 and 110
mm long, optionally provided in sets. Optionally, different set
sizes are provide din increments of 10 mm. in this and other
embodiments, increments of different sizes for tools and components
may be used, for example, 5 mm, 7 mm, 12 mm, 15 mm and/or smaller,
intermediate or greater increments. In addition, the increments may
be non-linear, for example, becoming larger for larger
implants/bone. Optionally the rods have consecutive segments with
different diameters
[0400] While solid rods are shown, in some embodiments, the rods
are hollow, at least along part of their length. Optionally, the
hollows are used for injecting cement through the rod. Optionally
or alternatively, the rod is held (for carrier 1800) from within a
hollow thereof, rather than from outside, for example, using a
narrow pin or spring element.
[0401] While round cross-sections are shown, in some embodiments,
other cross-sections are provided, for example, triangular, square,
rectangular and hexagonal. The shape may be rotationally symmetric
or not. Optionally, different rods for a same implant have
different cross-sections.
[0402] In an exemplary embodiment of the invention, different rods
for a same implant have other variations in proprieties, for
example, type, shape, finish, length, strength, flexibility,
diameter and/or material. Optionally, the selection is such as to
support better interlocking of the rods and/or to prevent the rods
forming a seal against cement flow in the implant.
[0403] In an exemplary embodiment of the invention, a rod can be
non-uniform in cross-section, for example, have more fibers near an
inside or an outside thereof.
[0404] In an exemplary embodiment of the invention, the rods are
selected to be at least 30%, 50%, 70%, 80%, 90% or intermediate or
greater length percentages of the final implant.
[0405] In an exemplary embodiment of the invention, the rods are
shaped and/or finished to enhance cement adhesion thereto and/or to
enhance cement flow inside the implant as it is being
constructed.
[0406] FIG. 23B shows a rod 2350 including various exemplary means
to enhance cement adhesion, in accordance with exemplary
embodiments of the invention.
[0407] As shown a shaft 2352 includes a plurality of ridges 2358,
which may be, for example, abrupt or gradual. For example, the
profile of the rod (axially) may be sinusoidal. The pattern may be
uniform along the rod or it may change, for example, monotonically
or in a manner whereby the rods do or do not match each other.
[0408] Optionally or alternatively, surface treatment 2362 may be
provided, for example, by sand blasting or chemical or plasma
etching, to enhance cement adhesion.
[0409] Optionally or alternatively, one or more voids or
passageways 2360 may be provided for cement flow therethrough.
[0410] Optionally or alternatively, one or more protrusions (not
shown) may be provided on the rod, for example to enhance inter-rod
locking and/or cement adhesion.
[0411] Optionally, threading and/or reverse-threading is provide
don the rod. Optionally, the threading is used to carrier and/or
advance the rod and/or retract the rod out of the implant, if
needed.
[0412] Optionally or alternatively, the cross-sectional shape
and/or orientation of the rod change along its length.
[0413] An optional rounded end 2354 and an optional inclined end
2356 are also shown.
[0414] In some embodiments, tensile elements are pre-soaked with
set or non-set cement.
[0415] In an exemplary embodiment of the invention, the tensile
elements are configured to be substantially non-extending.
Optionally, the rods are configured so that an extension of up to
10%, 5%, 3%, 1%, 0.5%, 0.3% or smaller or intermediate values can
be expected under bone stress conditions
[0416] While, in some exemplary embodiments of the invention, the
rods do not anchor to bone, optionally, some anchoring ability is
provided, for example, threading, sharp points and/or hooks
integrally formed thereon. Optionally, such rods are used with an
enclosing bag or outside of such a bag. Optionally, the tip of such
a rod is pushed through a bag into surrounding bone.
Exemplary Bag Design
[0417] In an exemplary embodiment of the invention, the bag is
formed as a mesh or other porous fabric, such as a knit. Optionally
or alternatively, at least some of the bag is non-porous and
includes one or more opening. Optionally or alternatively, openings
are provided in a porous bag. In an exemplary embodiment of the
invention, the bag is generally tubular or ovoid. Alternatively,
other shapes may be provided, for example, as described below.
Various cross-sections can be provided, for example, circular,
rectangular and/or triangular. Optionally, one or more corner
reinforcement elements (e.g., a metal fiber) is provided along
angles of the cross-sections. Optionally, is twisted, for example,
in the form of a twisted triangle. Optionally or alternatively, the
bag is spiral. In an exemplary embodiment of the invention, the bag
is made of one or more of Dyneema Purity.RTM. fibers, Kevlar,
aramid and/or polyethylene. Optionally or alternatively, other
fibers such as described above may be used. Optionally, different
fiber types and/or thickness are used for longitudinal and
circumferential directions. Optionally, the weave is not parallel
to the main axis of the bag. Optionally, but not necessarily, the
bag is sealed at its end. Optionally, the bag is forked. One or
more ribbons (e.g., in shape of a ring) of other materials, such as
metal may be provided along the bag.
[0418] In an exemplary embodiment of the invention, the mesh
diameter is between 2.5 and 25 mm, for example, between 5 and 15
mm, for example, 10 mm. IPA the length of the mesh bag is between
20 and 200 mm in length, for example, between 50 and 130 mm in
length, for example, 100 mm in length. Optionally, an additional
length of 3-15 mm may be provided for attachment onto delivery
tools.
[0419] In an exemplary embodiment of the invention, the distal end
of the bag is sealed, for example, by tying a knot, by a plug such
as a metal mushroom-shaped plug such as shown in FIG. 10B.
Optionally, such a plug is radio opaque, prevents rod penetration,
holds stylet 1400 and/or holds rod 1068. Optionally or
alternatively, the distal end is reinforced by the addition of one
or more metal fibers (or woven or knit sections) to the mesh,
optionally as part of the weaving, optionally as an embroidery.
[0420] Optionally or alternatively to a bag, a mesh or other
radially expandable stent design may be used. Optionally or
alternatively, the end of the bag is unsealed.
[0421] In an exemplary embodiment of the invention, pores are
formed in the bag, for example, of diameter 0.1 mm. Optionally,
additional pores for forming anchor sections or other large cement
leaks are provided. Optionally, such additional pores are provided
by inserting a needle into the mesh and optionally tying a suture.
Optionally the pores are formed by the pattern of weaving or
knitting of the bag.
[0422] FIG. 26 shows a pore 2610 formed in a mesh section 2600, in
accordance with an exemplary embodiment of the invention. While the
weave is shown to be generally open, this is for clarity. In an
exemplary embodiment of the invention, the weave is tight, in some
cases tight enough to prevent significant leakage and/or sweating
of cement.
[0423] In the weave shown, a plurality of longitudinal fibers 2602
are woven with a plurality of circumferential fibers 2604.
Optionally, at pore 2610, a circumferential fibers 2608 bends back
and does not complete the circumference. Optionally or
alternatively, a second circumferential fiber 2606 also folds back
at pore 2610. Thus, pore exhibit only unidirectional weaving, as
compared to multi-directional weaving at other places (or the
weaving is multi-directional but of a lower order. Optionally, one
or more longitudinal fibers 2602 lies inside the pore and has no
circumferential weaving holding it (the figure shows an embodiment
with no such fibers).
[0424] Pore size is optionally varied by increasing the number of
fibers 2606, 2608 in the longitudinal direction, that are folded
over. Optionally or alternatively, pore sizes are varied by folded
over fibers 2606 and/or 2608 retracting the longitudinal
fibers.
[0425] In an exemplary embodiment of the invention, a plurality of
different pore sizes are provided in a bag. Optionally or
alternatively, a different in seepage behavior along the bag is
provided by changing a pore density along different regions (axial
and/or circumferential) of the bag. For example, two regions (with
seepage) can have a difference of 10%, 20%, 50%, 90%, 100%, 200%,
300% or smaller or intermediate or greater percentage in density of
pores and/or total pore cross-section. In some embodiments, such
percentages reflect also mesh-inherent pore sizes.
[0426] In an exemplary embodiment of the invention, a same bag may
be used to provide different degrees of leakage, for example, based
on the indication and/or implant properties desired. Optionally, a
table is provided suggesting which mesh to and cement pair to use
with which need. Optionally or alternatively, a pressure used to
inject the cement may depend on the viscosity of the cement, for
example, as measured directly using a sensor (not shown) or based
on a mixture and setting time elapsed.
[0427] In some embodiments, the bag is straight. Alternatively, in
some embodiments the bag is configured to have a curved shape along
some of its length (e.g., a "J"-shape) or all of its length (e.g.,
a "banana" shape). In some embodiments, the bag is parallel walled.
Alternatively, the walls of the bag are not parallel and are
sinusoidal or include bulges. Optionally or alternatively, the bag
has circumferential changes, for example, the bag being fluted
(having elongate sections that extend radially or are depressed).
In embodiments, the walls of a bag are made of filaments having
homogenous properties. Alternatively, in embodiments, a bag is made
of filaments having different properties, for example different
strength and/or elasticity.
[0428] In embodiments, a container is open or is provided with a
perforated wall (with perforations of up to about 0.04 mm.sup.2)
allowing air to escape through the holes when a cement material is
injected therein.
[0429] In an exemplary embodiment of the invention, bag elongation,
if any (e.g., 1%, 3%, 5%, 10%, 20% or greater or intermediate
values) and/or bag circumferential stretching, are a property of
the weave used. Optionally or alternatively, such elongation or
stretching is a property of the fiber used. In an exemplary
embodiment of the invention, circumferential expansion is not
coupled to axial expansion/retraction.
[0430] In additional exemplary embodiment of the invention, the
container, and/or the tensile element fibers, and/or the tensile
element matrix, and/or the bone cement are made of bioabsorbable
material. Optionally, at least 20%, 50% or more by volume of the
introduced materials are bio-absorbable.
Exemplary Bag Attachment and Detachment
[0431] FIG. 24A-24D illustrate bag attachment methods in accordance
with an exemplary embodiment of the invention.
[0432] FIG. 24A shows a bag 2402 attached to an introducer tube
2404, by a neck 2410 of the bag being pressed against a recess 2406
of the tube, by a metal band 2408. Optionally, neck 2410 is formed
of a different material and/or different weave than the rest of bag
2402. Alternatively, the band is inside the tube, rather than
outside.
[0433] FIG. 24B shows an embodiment where a bag 2422 is attached to
a delivery tube 2424 by an elastic ring 2428 that engages the bag
against an optional recess 2426.
[0434] FIG. 24C shows an embodiment, where a suture 2438 is used to
attach a bag 2432 to a delivery tube 2434. Optionally, tube 2434
includes a plurality of apertures 2436, for suture 2438 to pass
through. Optionally, the bag is released by cutting or releasing
the suture.
[0435] FIG. 24D shows an embodiment where a bag 2440 includes a
wider section 2442 and a narrower section 2444 sized to exactly fit
on a delivery tube and engage it by friction. Optionally, the neck
of this or other bags includes a friction enhancing layer, to
reduce inadvertent slippage off the delivery tube.
[0436] In an exemplary embodiment of the invention, adhesive is
used to attach the bag to the delivery tube, in addition to or
instead of other means.
[0437] In some embodiments, the bag extends to outside the body and
acts as a cannula or is provided within cannula 110.
[0438] Optionally, in some of the above embodiments, when
sufficient axial force is applied, the bag releases from the
recess. It is noted that with rods inside, the bag is typically
wider than the opening in the cortical bone. Optionally or
alternatively, bags 2402 and/or 2422 can be released by cutting the
bands.
[0439] In an exemplary embodiment of the invention, the end of the
delivery tube includes one or more apertures and/or weakening, so
that when the tube is twisted, the tube breaks off and stays in the
body with the bag. Optionally, the twisting serves to close
proximal the end of the bag.
[0440] FIG. 25 illustrates a sleeve cutting tool 2500, in
accordance with an exemplary embodiment of the invention.
[0441] A shaft 2502 includes a plurality of bent-in sections 2504
(may be a single slotted tube section), which include a cutting
edge 2506. When a cone or other widening element 2508 is retracted
(e.g., by pulling on a wire 2510), the bent-in sections extend
outwards a bag section that is contacted by the cutting edge may
thereby be cut. Optionally, the cutting is against an enclosing
tube, such as that of cannula 1100 and/or the bag holder. The bag
may be held on the outside or on the inside of the bag holder, as
shown herein in various embodiments.
[0442] Alternatively or additionally, to using a cone, the cutter
may be elastically or super-elastically predisposed to extend out
radially. Such a cutter may be formed, for example, of stainless
steel or Nitinol.
[0443] Optionally or alternatively, a non-concentric blade (e.g., a
tube with an extension including a blade which is bent inwards by
an enclosing tube, such as cannula 1100) is used to cut the bag.
Optionally, the cutting tool is rotated to perform the cut.
Exemplary Implant Location
[0444] In an exemplary embodiment of the invention, the bone is a
leg bone (e.g., femur, tibia, fibula) an arm bone (e.g. humerus,
ulna, radius), foot and hand phalanges or a clavicle. Optionally,
the implant is used to repair a non-displaced fracture, such as a
trochanter fracture and/or used to repair a reduced fracture.
[0445] In an exemplary embodiment of the invention, when repairing
a trochanter, the implant rest son the bone (cortex) at two or
three points. Optionally, multiple resting points are provided for
other bones as well. In the example of the trochanter, three
resting pints are optionally provided--the cortex where the implant
is inserted, the inside of the femur neck, optionally midway along
the femur neck, and the distal end of the implant rests on
trabecular bone inside the ball of the femur.
Exemplary Implant Mechanical Properties
[0446] In an exemplary embodiment of the invention, the implant is
constructed to have certain desirable properties. It should be
noted that the implant as in some of the embodiments described
herein is inherently personalizable, by modifying one or more of
rod type, size, shape and number, mesh type, cement type and
size.
[0447] In an exemplary embodiment of the invention, one or more
implant parameters are selected to match a particular need of a
patient, while optionally minimizing implant size. In an exemplary
embodiment of the invention the number of rods and/or diameter of
selected rods is personalized for a patient. Optionally, such
adaptation allows implant elasticity modulus to be selected as a
function of patient condition, such as bone mineral density and/or
Young modulus.
[0448] Optionally, bone properties are measured using drill 1200,
or otherwise during the procedure, so that an implant
personalization decision can be made on the fly. In an exemplary
embodiment of the invention, bone properties are assessed by one or
more of ultrasonic measurement of elastic properties, x-ray
measurement of porosity and/or density, biopsy and/or analysis of
residue by drilling. Optionally, difficulty in drilling and/or
resistance to slow rotation of the drill with a side element
extended, is used to assess a strength of the bone. Optionally,
personalization can vary one or more of the above mentioned implant
mechanical properties by 10%, 20%, 30%, 40%, 60% or more, up and/or
down.
[0449] In an exemplary embodiment of the invention, one or more of
the following considerations is used: initial give as compared to
bone give, so as to allow bone to work; resistance to further give
at a point where bone does not break yet; and/or total strength.
Optionally or alternatively, the implant design may be determined
by the direction and/or type of force expected. Optionally, implant
properties are varied by changing one or more of rod diameter, rod
type, rod length, rod finish, bag length and/or diameter and/or
cement properties. Optionally, at least some of these properties
can be varied by selecting items from a kit which includes a range
of possible elements. Optionally, a table is provided to choose
implant constitutes for a desired effect.
[0450] In an exemplary embodiment of the invention, the implant is
used in bones in locations that experience forces addition to
compression forces, for example, experiencing tension, shear and/or
rotation forces.
[0451] In an exemplary embodiment of the invention, cement leakage
locks the implant to bone so such forces are passed from bone to
implant along substantially its entire length. Optionally, rod
design and density and/or chemical bonding and/or mesh behavior
assist in such functionality.
[0452] In an exemplary embodiment of the invention, the implant is
configured to have an elastic modulus of between 30-40 GPa.
Optionally or alternatively, the elastic modulus is less than 30 or
less than 5 Gpa. Optionally or alternatively, the elastic modulus
is less than 100 or less than 80 Gpa.
[0453] In an exemplary embodiment of the invention, the implant is
configured to have an elastic modulus similar to that of trabecular
bone, for example, within 50%, 20%, 10% or smaller or intermediate
values. Optionally, different parts of the implant have different
values, for example, by using rods with axially varying properties
and/or using rods of a plurality of lengths.
[0454] In an exemplary embodiment of the invention, the rods are
evenly distributed in the implant. Optionally or alternatively, the
rods are centered around a center of the implant. Optionally or
alternatively, the rods are concentrated around an outside of the
implant. Optionally, the rods are moved outwards by the injection
of the cement and/or insertion of stylet.
[0455] In an exemplary embodiment of the invention, the implant is
formulated to have a density similar to that of surrounding bone
tissue, for example, within a factor of 3, 2, 1.5, 1.3, 1.1 or
intermediate or closer to 1 or even smaller than 1. Optionally,
implant density is modified by suitable selection of implant
constituents and/or by adding low density particles, for example,
hollow spheres.
[0456] It is important to note that generally, a greater
proportional amount of non-rigid tensile elements provides an
implant of the present invention with greater flexibility while a
greater proportional amount of cement provides less flexibility. In
exemplary embodiments of the invention, an implant includes at
least 20%, 30%, 45%, 60% or more or intermediate percentages by
volume of longitudinal tensile elements. The relative amounts of
cement to tensile elements making up a specific implant is
determined by a user, for example, in accordance with one or more
of the nature of the cement, the nature of the tensile elements and
the desired degree of flexibility and strength of the implant. In
embodiments, an implant comprises a plurality of different tensile
elements having different tensile properties allowing for
non-linear effects.
[0457] In an exemplary embodiment of the invention, implant size is
reduced by considering the quality of bone binding by the implant
and/or quality of binding of implant parts to each other.
Optionally, the bone binding is enhanced by cement
inter-digitations, cortical anchoring, leaning on cortex at
additional point(s) and/or cement bulbs for anchoring in trabecular
bone.
Considerations for Entry Diameter
[0458] In some embodiments of the invention, the size of the bone
entry hole and/or skin entry hole are important; to reduce trauma
to an already weakened bone, for example.
[0459] In an exemplary embodiment of the invention, one limitation
on hole size is the time it takes to insert a sufficient number of
small rods and achieve a desired implant diameter. In some
embodiments, the limitation is caused by the smallest diameter of
the mesh bag. Optionally, the bag thickness is tradeoff with the
properties of other tensile elements. In some embodiments, the
limitation is that of the drilling elements, which need some
rigidity for mechanical drilling and/or the time it takes to widen
the cavity.
[0460] In some embodiments, cannula 1100 does not enter cortical
bone. However, this presents a possible danger that the bag will
not lay properly.
[0461] Various embodiments are described herein which allow a
physician to trade off the various options and select a tool set
and implant design which meets his needs while minimizing access
pathways.
[0462] In an exemplary embodiment of the invention, the procedure
is carried out using a cortical entrance diameter of between 3 and
5 mm and a cavity diameter of 10 mm. Optionally, the cavity/implant
diameter is between 2 and 4 times the entry diameter, for example,
.times.2 .times.3 .times.4 .times.5 .times.6 or intermediate or
greater ratios.
General
[0463] Implementation of the method and/or system of embodiments of
the invention can involve performing or completing selected tasks
manually, automatically, or a combination thereof. Moreover,
according to actual instrumentation and equipment of embodiments of
the method and/or system of the invention, several selected tasks
could be implemented by hardware, by software or by firmware or by
a combination thereof using an operating system.
[0464] For example, hardware for performing selected tasks
according to embodiments of the invention could be implemented as a
chip or a circuit. As software, selected tasks according to
embodiments of the invention could be implemented as a plurality of
software instructions being executed by a computer using any
suitable operating system. In an exemplary embodiment of the
invention, one or more tasks according to exemplary embodiments of
method and/or system as described herein are performed by a data
processor, such as a computing platform for executing a plurality
of instructions. Optionally, the data processor includes a volatile
memory for storing instructions and/or data and/or a non-volatile
storage, for example, a magnetic hard-disk and/or removable media,
for storing instructions and/or data. Optionally, a network
connection is provided as well. A display and/or a user input
device such as a keyboard or mouse are optionally provided as
well.
[0465] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable subcombination
or as suitable in any other described embodiment of the invention.
Certain features described in the context of various embodiments
are not to be considered essential features of those embodiments,
unless the embodiment is inoperative without those elements.
[0466] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the spirit and broad scope of the appended claims. All
publications, patents and patent applications mentioned in this
specification are herein incorporated in their entirety by
reference into the specification, to the same extent as if each
individual publication, patent or patent application was
specifically and individually indicated to be incorporated herein
by reference. In addition, citation or identification of any
reference in this application shall not be construed as an
admission that such reference is available as prior art to the
present invention.
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